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1960

Journal of the Lepidopterists' Society

37

STUDIES OF THE CHROMOSOMES OF

NORTH AMERICAN RHOPALOCERA

2. HESPERIlDiE, MEGATHYMID^E, AND PIERIDAE

by Kodo Maeki and Charles L. Remington

The first of this series of papers was on eleven species of Papilionidae and included an introduction and a description of the sources of our material and of the techniques we use (Maeki & Remington, 1960). The present paper is a continuation of the first and covers species of the two families of the super-family Hesperioidea and the family Pieridae. The remaining families are being covered in two papers immediately following this one. The numbers in square brackets are the designations of individuals studied and can be found on the specimens and slides preserved for permanent reference in the Peabody Museum of Yale University. In the following lists "n" represents the hap-loid chromosome number, "I" refers to the primary spermatocyte division and "II" to the secondary spermatocyte division. No female meiosis was investigated in these three families.

Most of the specimens for which the chromosomes are reported here were taken in 1959, the principal exception being the interesting genus Erynnis. We extracted our 1960 Erynnis data and inserted it as the manuscript was going to press. Counts for many additional species of Papilionidae, Pieridae, and Hesperiidae are being made from 1960 material and will be published in a supplementary paper. We have also worked up about two dozen species of African Rhopalocera collected by S. A. Hessel in 1960, including 7 Pieridae. These are being reported separately from the present North American series.

We found no meiotic divisions in males of the following species: two Oarisma garita (Reakirt), three Polites draco (Edwards), one Hesperia (colorado Scudder?), and one Pyrgus communis (Grote) from Colorado; one Ancyloxipha nurnitor (Fabricius), and one Hesperia leonardus (Harris) from Connecticut; fourteen Erynnis brizo somnus (Lintner) from Florida; one Megathymus y. yucca' (Boisduval & Leconte) from Georgia; and two Agathymus estellea; (Stallings & Turner) from Mexico. Hesperioids in general tend to have meiosis completed before or soon after eclosion, and it is necessary with some species to try several young males or even pupae to get suitable divisions.

A. HESPERIID^:

1. Achalarus toxeus (Plotz). The haploid chromosome number is 16 but there was a single exception. Unequivocal counts of 16 were made in 24 nuclei in the primary spermatocyte division and 32 nuclei in the secondary spermatocyte division; a single secondary spermatocyte division showed 17

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Maeki & Remington: Chromosomes

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chromosomes. All 57 nuclei were in the testes of a single male [M21] taken at Ciudad Victoria, Tamaulipas, Mexico, 1 August 1959. In all of the 16-chromosome nuclei there are 15 larger chromosomes and 1 smaller unit. Since the 17-chromosome nucleus shows 14 larger chromosomes and 3 smaller units, it is reasonable to suppose that 2 of the 3 small bodies are normally fused into a single element in A. toxeus. Most cytologically known species of this subfamily (Pyrginx) have 31 or 30 as the haploid number. The normal 16 of A. toxeus may have evolved by 1 +1 fushions of 30 of the ancestral 31 small elements. The unusual nucleus with 17 suggests that at least one of the fusions is sometimes unstable.

2.      Chioides catillus (Cramer). N = 31. Counts were made in 4 nuclei (I) in the testes of one male [M 20] taken at Cuidad Victoria on 1 August. There is considerable diversity in size, 6 or 7 of the chromosomes being larger than the others. This male was somewhat old, and the testes were full of spermatozoa and connective tissue, with very few dividing cells.

3.      Erynnis icelus (Scudder & Burgess). N — 30. Counts were made in 30 nuclei (T) and 16 nuclei (II) in testes of 2 males [461, 467] taken at the mouth of Nettleton Hollow, Woodbury, Litchfield Co., Connecticut, 28 May 1960, by C. L. Remington. As with E. juvenalis, 5 chromosomes are small, about 20 medium, about 4 large, and 1 very large. We have also studied chromosomes of an apparently new species in Connecticut which is a foodplant sibling of E. icelus. The new sibling also has n i= 30.

4.      Erynnis juvenalis (Fabricius). N l== 30. Counts were made in 10 nuclei (I) and 8 nuclei (II) from one male [476] taken at Nettleton Hollow, Woodbury, Litchfield Co., Connecticut, 28 May 1960. No meiotic divisions were found in 4 other males taken at the same time nor in 1 male taken at Lakehurst, New Jersey, 7 May 1960. As with other Erynnis, 5 chromosomes are small, 20 medium, 4 larger, and 1 distinctly the largest.

5.      Erynnis horatius (Scudder & Burgess). N— 31. Counts were made in 4 nuclei (I) and 8 nuclei (II) in the testes of 2 males [F76, F196] taken 18 and 24 April 1960 at the Archbold Biological Station, Highlands Co., Florida, by Kodo Maeki. The determinations were checked by John M. Burns. Apparently 5 chromosomes are small, 5 large, and the others medium.

6.      Erynnis persius (Scudder). N '= 31. Counts were made in 15 nuclei (I) and 10 nuclei (II), in the testes of 3 males [462, 463, 465] taken at Nettleton Hollow, Woodbury, Litchfield Co., Connecticut, 28 May 1960, bv C. L. Remington. Determinations were checked by John M. Burns. The size relations of the chromosomes are like those of E. horatius.

7.      Erynnis baptisue (Forbes). N — 31. Counts were made in 78 nuclei (I) and 34 nuclei (II) from 3 males [402-1, 402-2, 402-3] reared on Baptism tinctoria from one wild mother taken in New Haven, Connecticut, by R. W. Pease, Jr., and emerging ex-pupis on 6 October 1959. The testes were fixed the day the males emerged, and meiotic divisions were numerous. About 16 of the chromosomes are larger than the others. (See E. lucilius, below, for discussion of a probable hybrid.)

CHROMOSOMES

PLATE 1

Fig. la — Achalarus toxeus (I); fig. lb — same (II; n = 16) ; fig. lc — same (II; n = 17) ; fig. 2 — Chioides catillus (I) ; fig. 3a — Ochlodes sylvanoides (I); fig. 3b — same (II); fig. 4a — Nastra I'herminieri (I) ; fig. 4b — same (II) ; fig. 5 — Megathymus violce (II) ; fig. 6a — Stallingsia maculosa (I) ; fig. 6b — same (II) ; fig. 7a — Agathymus maria (I); fig. 7b — same (II). [On plates 1-5: I t= primary spermatocyte division, II != secondary spermatocyte division; magnifications all 3900 diameters; drawings made with camera lucida.]

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Maeki & Remington: Chromosomes

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8.     Erynnis lucilius (Scudder & Burgess). N = 31. Counts were made in testes of 2 males reared from larvae taken on Aquilegia canadensis on Rattlesnake Mt., Hartford Co., Connecticut, in June 1960 by R. W. Pease, Jr., and W. A. Christian. These emerged in late June and July, and the testes were fixed soon after eclosion. Counts of 31 were invariably obtained for male 617 in 15 nuclei (I) and 10 nuclei (II), and many other suitable nuclei could have been counted. There are 4 small, 11 large, and 16 intermediate chromosomes. Male 836 was apparently a wild hybrid, since the 21 countable metaphase nuclei (all 1st spermatocyte) showed the following chromosomal tally:

chromosome no. (n) — 32 33         34 35         36 37

number of nuclei        —           4          4          2          3          5           3

apparent univalents

(extra tiny elements)               2          4          6          8         10         12

This suggests that the other parent of the hybrid was a 31-chromosome species, and distributional facts point to E. baptisice. Probably the female parent was E. lucilius, since the egg was laid on the lucilius foodplant. The few secondary spermatocytes were not satisfactory for counting.

9.     Grais stigrnaticus (Mabille). N — 31. Counts were made in 37 nuclei (I) and 22 (II), in the testes of 2 males [M23-6, M23-7] taken at Ciudad Victoria on 1 August. Of 11 males whose testes were fixed, meiotic divisions were found only in these 2. Most of the specimens were collected at muddy spots in a river bed. There is some diversity in the sizes of the chromosomes, with about 8 being smaller than the others.

10.     Ochlodes sylvanoides (Boisduval). N = 29. Counts were made in 17 nuclei (I) and 14 nuclei (II), in the testes of 2 males [275, 276] taken near Somerset, Gunnison Co., Colorado, on 15 August 1959. No meiotic divisions were found in the testes of 6 other males taken at the same time. Especially in the secondary spermatocyte 2 of the chromosomes are much larger than the other 27, suggesting 1 + 1 fusions of 4 of 31 ancestral chromosomes.

11.     Nastra Therniinieri (Latreille). N = 30. Counts were made in 12 nuclei (I) and 5 nuclei (II), all in a single male [329] taken on West Rock, New Haven, Connecticut, on 5 September 1959. It was clearly observed that 5 of the chromosomes in the primary spermatocytes are about one-half as large as the other 25. The few secondary nuclei were somewhat oblique in our sections, and size differences could not be safely estimated.

B. MEGATHYMID^:

1. Megathymus viola Stallings & Turner. N — 27. Counts were made in 5 nuclei (II) in a single male [417] reared at Yale from an egg collected 29 July 1959 at 4000' on Yucca treculeana on the highway pass over the Sierra de la Gavia, Coahuila, Mexico. The testes were fixed immediately af-

CHROMOSOMES

PLATE 2

• • •                       • • • • *

• ••••                    •!•••• ••••••

VV.V/.*        .<&• -V^*'

8a •»•                    9a • ••                 i0a ##

•!•*:••             •••„•.•             ••••••

• •••••                         •:•••                     •«••!•;•

•••                            9b :••                     iob • •

• •••.•                   • •••••

• ••• • •                  •!•-••                   •• •

• • ••                    ••••                  •••• •

Ha        • •                      iza           # •

9 « »w w 13 • *•

• •••••                          • • • •

nb •;•:•                        12b *•*.•

• •                            * * •

. • • •                        •••

• •

••••• •                        ••••

• • ••

•-                        "•••

14a

• *                    14b •••«

Fig. 8a — Erynnis icelus (I) ; fig. 8b — same (II) ; fig. 9a — E. juvenalis (I) ; fig. 9b — same (II) ; fig. 10a — E. horatius (I) ; fig. 10b — same (II); fig. 11a — E. persius (I) ; fig. lib — same (II); fig. 12a — E. baptisia (I) ; fig. 12b — same (II) ; fig. 13 — E. luctlius (I) ; fig. 14a — Grats stigmaticus (I) ; fig. 14b — same (II).

41

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Maeki & Remington: Chromosomes

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ter eclosion the morning of 31 December 1949, and fortunately there were still a few dividing cells, none at the first division. All the chromosomes are similar in size.

2.     Stallingsia maculosa (H. A. Freeman). TV — 50. Counts were made in 23 nuclei (II) in testes of a pupa [424] ready to hatch and 22 nuclei (I) and 46 (II) in testes of a very young pupa [425]. Both were dissected on 2 April 1960. They had recently been collected as mature larvae by Don B. Stallings at Floresville, Wilson Co., Texas. One of the chromosomes is much larger than the other 49.

3.     A gathytnus mar ice (Barnes & Benjamin). N = 21. Counts were made in 5 nuclei (I) and 4 nuclei (II) all from a single newly hatched male [398] which emerged 28 September 1959 and had been collected as a blue larva in early August, 51/2 miles east of Langtry, Val Verde Co., Texas, in Agava lecheguilla Torrey by C. L. Remington. Two chromosomes are larger than the other 19.

C. PTERID^:

1.     Euchloe ausonides Lucas. N" = 31. Counts were made in 17 nuclei (I) and 6 nuclei (II), all from a single male [45-1] taken at Gothic, Gunnison Co., Colorado, 19 July 1959. No dividing cells were found in the testes of a second male taken at the same place. All the chromosomes are similar in size.

2.     Calias eurytheme Boisduval. N = 31. Counts were made in 53 nuclei (I), and 34 nuclei (II), in testes of 4 males [316-1, 316-a, 316-b, 354] taken in New Haven Co., Connecticut, 3 and 11 Sept. 1959. There are

7  large, 19 medium-sized, and 5 small chromosomes.

3.     Colias philodice Godart. TV ■— 31. Counts were made in 74 nuclei (I) and 62 (II), from 9 males taken in New Haven Co. from 3 to 19 Sept. 1959 [315-1, 315-2, 31,5-3, 315-4, 315-6, 315-7, 330, 352, 382]. About 7 or

8  chromosomes are larger than the others. Wild hybrids of C. philodice X eurytheme were also studied and showed no failure of pairing at first meiotic metaphase ; these are being reported elsewhere in a separate paper on cytology of wild hybrids.

4.     Colias alexandra Edwards. AT" = 31. Counts were made in 58 nuclei (I) and 17 nuclei (II) from testes of 3 males [82, 154, 162] taken at Gothic from 22 to 30 July 1959; testes of a fourth male showed no meiotic divisions. Several of the chromosomes are more or less larger than the others.

5.     Colias scudderii Reakirt. N ^ 31. Counts were made in 40 nuclei (I) and 22 nuclei (II) from testes of 6 males [3, 17, 19, 29, 129, 131] taken at Gothic from 17 to 27 Julv 1959. There are 5 or 6 chromosomes which are larger than the others. Wild hybrids of C. scudderi X alexandra showed some failure of meiotic pairing; as with C. philodice X eurytheme these studies are being reported elsewhere.

CHROMOSOMES

PLATE 3

•!*••• ••••• ••••• ••••

15a                             15b                                      16a

•# ••• #

• • •t*r**»               w^« -•iw w •••••

• • •                •                            • # •

• - ••            nu                                    18a                                  18b

# ~                17b

17a

•:•• ;••..• .:*•:. •••••

.•••V» •:•::• ••:••:• ••.-.••••. •••:••• ••.••• ••::•: •:••••

19a

••>V ••/•*.:■ •••#•• • ...

21a        *# *                  21b

Fig. 15a — Euchloe ausonides (1) ; fig. 15b — same (II) ; fig. 16a — Colias eury theme (I) ; fig. 16b — same (II); fig. 17a — C. philodice (I) ; fig. 17b — same (II) ; fig. 18a — C. alexandra (I); fig. 18b — same (II) ; fig. 19a — C. scudderii (I) ; fig. 19b — same (II) ; fig. 20a — C. meadii (I); fig. 20b — same (II) ; fig. 21a — '/erene cesonia (I) ; fig. 21b — same (II).

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Maeki & Remington: Chromosomes

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6.     Co lias meadii Edwards. 2V>=31. Counts were made in 15 nuclei (I) and 12 nuclei (II) from 3 males [189, 216, 218] taken in Gunnison Co., Colorado, found at Copper Lake, el. 10,500', on 2 August, and Cumberland Pass, el. 11,500', on 11 August 1959. As with other high altitude butterflies, dividing cells and also germ cells were few in number. About 7 or 8 chromosomes are large, 4 or 5 small, and the remainder medium-sized.

7.     Zerene cesonia (Stoll). AT != 31. Counts were made in 26 nuclei (I) and 23 nuclei (II) all in the testes of a single male [M7] taken at Ciu-dad Victoria, 1 August 1959. About 15 chromosomes are somewhat larger than the others.

8.     Anteos clorinde (Godart). N = 31. Counts were made in 41 nuclei (I) and 46 nuclei (II) in testes of 5 males [M6-1, M6-3, M6-4, M6-5, M6-6] taken at Ciudad Victoria, 1 and 2 August 1959. There is some diversity of chromosome size.

9.     Phcebis philea (Johansson). N — 31. Counts were made in 53 nuclei (I) and 39 nuclei (II) in testes of 7 males [M5-1, M5-2, M5-3, M5-4, M5-5, M5-6, M5-7], taken at Ciudad Victoria, 1 and 2 August 1959. There is some diversity of chromosome size.

10.     Kricogonia lyside (Godart). N <= 31. Counts were made in 81 nuclei (I) and 58 nuclei (II) in testes of 7 males [M28-1, M28-2, M28-3, M28-4, M42-1, M42-2, M42-3] taken at Ciudad Victoria, 1 and 2 August 1959. The chromosomes are all similar in size. Assuming that two species, K. lyside and K. castalia (Fabricius), were present at Ciudad Victoria, we had separated two groups of males and their fixed testes. It is believed by present taxonomists that these two "species" represent only one. The chromosomes being indistinguishable in our two groups, we can offer no cytological test of the species question in Kricogonia. It is possible, of course, that most closely related but discrete species show no conspicuous chromosomal differences.

11.     Eurema proterpia (Fabricius). N ~ 31. Counts were made in 30 nuclei (I) and 32 nuclei (II) in testes of 2 males [M31-1, M31-2] taken at Ciudad Victoria, 2 August 1959. As with other Eurema, there is little size difference among the chromosomes.

12.     Eurema mexicana (Boisduval) or E. boisduvaliana Felder & Fel-der. N '= 31. Counts were made in 24 nuclei (I) and 33 nuclei (II) in testes of one male [M37-2] taken 2 August at Ciudad Victoria. In contrast to E. Visa, meiotic divisions were very numerous and the testes much larger. Unfortunately, in one vial testes were fixed together of two males which appeared in the field to be of the same species. When Dr. A. B. Klots checked the specimens, one proved to be E. boisduvaliana and the other E. mexicana, but meiotic divisions were present in testes of only one of the specimens and there is no way of knowing which. It is highly probable that both species have a haploid number of 31 since all 4 North American species studied by us show

CHROMOSOMES

PLATE 4

••••••

• •••

• •••

• •••

J;::.-

••-••

22a

• •#

22b

23a

• ••

#

#

•v.%

23b

• •

• • <

••••••:•

••%•••••

* • • A

:•.

• 2*

24a

24b

•w#

25 a

• •

• • ••

• ••• •

•  • •

25b

•'•I

• •••••

26a         ••

. ••• • • •••

26b

Stt***

27a ••*

•••■

27b

•■:•:•:

• • ••

•••• • •

•••••• •

• •••• •

•  • •

• • • • #« • •

•    •• •

•  \« • •

•  • ••

#  ••• •

• • •

28

29a

• ••

29b

Fig. 22a — Anteos clorinde (I) ; iig. 22b — same (II) ; fig. 23a — Phcebis philea

(I)  ; fig. 23b — same (II) ; fig. 24a — Kricogonia lyside (I) ; fig. 24b — same (II) ; fig. 25a — Eurema proterpia (I) ; fig. 25b — same (II); fig. 26a — E. mexicana or boisdwvaliana (I); fig. 26b — same (II) ; fig. 27a — E. nicippe (I) ; fig. 27b — same

(II)  ; fig. 28 — E. lisa (I) ; fig. 29a — Appias drusilla (I) ; fig. 29b — same (II).

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46                                       Maf.ki & Remington: Chromosomes                        Vol.14: no.l

this number; however the two known Japanese species show n ^= 29 and n = 31, respectively, and it will be essential to check the present case with unquestionably correlated specimens and testes.

13.     Eurenia nicippe (Cramer). N <= 31. Counts were made in 6 nuclei (1) and 15 nuclei (II) in testes of 2 males [M8-1, M8-2] taken at Ciudad Victoria, 1 August 1959.

14.     Eur etna lisa (Boisduval & Leconte). Ar — 31. Counts were made in 19 nuclei (1), in testes from 2 males [314-A, 314-B] taken at West Rock, New Haven Co., Connecticut, 3 Sept. 1959. The gonads were small and had few dividing cells, none in the secondary division.

15.     Appias drusilla (Cramer). AT = 32. Counts were made in 102 nuclei (I) and 76 nuclei (II) in testes of 6 males [M43-1, M43-2, M43-3, M43-4, M43-5, M43-6] taken at Ciudad Victoria, 2 August 1949. All the chromosomes are similar in size.

16.     Picris napi macdunnoughii Remington. N — 25. Counts were made in 18 nuclei (I) and 8 nuclei (II) in testes of 3 males [14, 15, 16] taken at Gothic, Colorado, 17 July 1959. All the chromosomes are similar in size.

Testes of one P. napi olcracea Harris fixed as soon as it eclosed from refrigerated pupae from Katonah State Park, Berkshire Co., Massachusetts, reared by H. P. Wilhelm, showed no dividing cells. It is essential to determine the precise count for this and other so called napi races in view of the count shown below for P. virginiensis and those for Palearctic populations (see Discussion, below).

17.     Pieris virginiensis Edwards. A^ = 26. Counts were made in 13 nuclei (I) and 2 nuclei (11) in testes of 2 males [426, 427] reared from larvae taken at New Ashford, Berkshire Co., Massachusetts, by W. J. Rein-thal. The pupae had been refrigerated since late summer 1959 and removed to 20°C on 2 April I960; both hatched 5 days later, and the testes were removed and fixed on the same morning. The chromosomes are like those of P. napi macdunnoughii but there is an additional very small element (see Discussion, below).

18.     Pieris rapa- rapa (Linne). A" = 25. Counts were made in 162 nuclei (I) and 106 nuclei (II), in testes of 13 males [322, 325, 326, 335, 338, 339, 340, 342, 343, 349, 350, 355, 383] taken in New Haven Co., Connecticut, 5 to 19 Sept. 1959. Without exception these 268 nuclei show exactly 25 elements. Thus the small "m-chromosome" present in the nucleus or the cytoplasm in the Japanese P. rapcc crucivora is not in the individuals we have studied from Connecticut. (See Discussion, below.)

19.     Pieris beckerii Edwards. Ar *=■ 26. Counts were made in 8 nuclei (I) and 6 nuclei (II) in testes of 2 males [35-1, 35-3] taken at Iola, Gunnison Co., Colorado, 18 July 1959, by R. W. Pease, Jr. A third male taken at the same time showed no meiotic divisions. All the chromosomes are similar in size.

CHROMOSOMES

PLATE 5

v—

30a

• ••• # •••••

• • •

:>7:

30b

# •

31a

•••V

• • • •

31b

32

.•:•

•.••••• •••••-•

33a

• • •

•••V • ••••

•••••

33b *•

• # • • • •*•

• •

• •

34a

34b

# • •••

e ••*••            35b '••

35a

36a

•   • •

•   • •

.!:

.}••..

•::.*:•

36b

• •*

Fig. 30a — Pieris rupee rapce (I); fig. 30b — same (II); fig. 31a — P. napi macdiinnottghii (I) ; fig. 31b — same (II); fig. 32 — P. virginiensis (I) ; fig. 33a — P. beckerii (I) ; fig. 3 3b — same (II) ; fig. 34a — P. occidentalis (T) ; fig. 34b — same (II) ; fig. 35a — P. calyce (I) ; fig. 35b — same (II); fig. 36a —Ascia monuste (I) ; fig. 36b — same (II).

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20.     Pieris occidentalis Reakirt. N *= 26. The chromosomes are all similar in size. This use of the name is not meant to imply any firm conviction on the relation of occidentalis to protodice Boisduval & Leconte or to calyce. The insect we are calling occidentalis is very similar to protodice of the eastern states and may well be the same species and not even a worthy subspecies. It tends to be fairly common at middle altitudes in Colorado, although it sometimes flies to the tops of the highest peaks. It should be remembered that in the East P. protodice is a characteristically restless butterfly with extensive emigration going on all the time; P. protodice is often found in Connecticut, sometimes even breeding in large numbers, but it is never a permanent resident and temporary colonies do not survive most, if any, winters. Its western population (or perhaps distinct species), occidental-is, apparently has the same long-distance movement and may turn up anywhere in Colorado. In contrast to Brown, et al. (1956), we regard calyce as a very different entity and are inclined to believe that it will be recognized as a distinct species when more is known of its biology (and perhaps morphology). It is consistently much smaller than occidentalis, is restricted to high altitudes (we know it well in Boulder County and Gunnison County), and has a different aspect in color, markings, and shape from all protodice-occidentalis populations known to us. The insect we call calyce is not the spring brood of occidentalis, which closely resembles form "vernalis" of the eastern protodice. None of these problems affects the use of chromosome characters with which this paper is concerned, because we have found no chromosomal differences between calyce and occidentalis. It would of course have simplified the taxonomy if calyce had turned out to have a different number, as P. virginiensis does. Our counts of occidentalis were made in 86 nuclei (I) and 47 nuclei (II) in testes of 4 males: 3 taken at Gothic, el. 9,500', Colorado, 28 and 29 July 1959, [143, 155, 156] and 1 male [278] taken near Somerset, el. 7,800', Colorado, 15 August 1959. All these males had large testes.

21.     Pieris calyce Edwards. N *= 26. Counts were made in 23 nuclei (I) and 9 nuclei (II) in testes of 5 males taken at Copper Lake, el. 10,500', Gunnison Co., Colorado, on 1 August [180-1, 180-2, 180-3, 180-5] and 7 August 1959 [204]. One of the [180] specimens seems to be occidentalis, not calyce. Three other males, from Copper Lake, Gothic, and Cumberland Pass, showed no meiotic divisions. The chromosomes are all similar in size. The gonads were rather small, and the chromosomes showed a poor affinity for the stain, a condition commonly found in Nymphalidse with imaginal winter diapause and in various high altitude butterflies. (See remarks under P. occidentalis, above).

22.     Ascia monuste (Linne). N '=■ 27. Counts were made in 14 nuclei (I) and 1 nucleus (II) in testes of 2 males [M4-1, M4-3] taken at Ciudad Victoria, 1 August 1959. A third male taken at the same time shows no meiotic divisions. One chromosome is much smaller than the others.

CHROMOSOMES

PLATE 6

Fig. 37a — Achalarus toxeus (I); fig. 37b — same (II; /?i= 16) ; fig, 37c — same (II; «=17) ; fig. 38 — Erynnis icelus (I) ; fig. 39 — E. persius (I) ; fig. 40 — E. baptisice (I) ; fig. 41 — Grais stigmaticus (I); fig. 42 — Ochlodes sylvanoides (I) ; fig. 43 — Nastra Yherminieri (I) ; fig. 44 — Euchloe ausonides (I) ; fig. 45 — Colias eurytheme (I) ; fig. 46 — C. philodice (I) ; fig. 47a — C. meadii (I) ; fig. 47b — C. meadii (II) ; fig. 48 — Zerene cesonia (I).

49

PLATE 7

CHROMOSOMES

; 4

WW

Fig. 49a — ^w/^j clorinde (I) ; fig. 49b — same (II) ; fig. 50 — Phcebis philea (I) ; fig. 51a — Kricogonia lyside (I) ; fig. 51b — same (II) ; fig. 52 — Eurema pro-terpia (I) ; fig. 53 — E. mexuana or boisduvaliana (II) ; fig. 54 — A ppias drusilla (I) ; fig. 55 — Pieris rapce rapce (I) ; fig. 56 — P. napi macdunnoughii (I) ; fig. SI — P. calyce (I) ; fig. 58 — P. oceidentalis (I) ; fig. 59 — P. beckeri (I) ; fig. 60a — Ascia monuste (I) ; fig. 60b — same (II).

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Table 2.1 CHROMOSOME NUMBERS OF THE HESPERIOIDEA.

Species

Number (n)

Divis

1. HESPERIID^E

Cceliadinae:

Bibasis aquilina (Speyer)                      29

Choaspes benjaminii (Guerin)             31 Pyrginae:

ACHALARUS TOXEUS (Plotz)     16

CHI OWES CATILLVS (Cramer)    31

Spialia orbifer (Hiibner)                       30

Pyrgus malvce (L.)                                  31

Pyrgus onopordi (Rambur)                 30

Pyrgus serratulce (Rambur)                  30

Pyrgus alveus (Hiibner)                        24

Carcharodus alcece (Esper)                    31

Carcharodus lavatherce (Esper)           30

Erynnis montanus (Brem.)                    31

Erynnis tages (L.)                                   31

ERYNNIS ICELUS (Scudd.&Burg.) 30 ERYNNIS JU VENA LIS (Fab.) 30 ERYNNIS HORAT1US (Sc. & B.) 31 ERYNNIS PERSIUS (Scudder)         31

ERYNNIS BAPTISIJE (Forbes) 31 ERYNNIS LUCILIUS (Sc. & B.) 31 GRAIS STIGMATICUS (Mab.) 31 Dairnio tethys (Men.)                            30

C. Hesperiinae:

Thymelicus lineola (Ochs.)                   29

Ochlodes venata (Br. & Grey)          29 (28)

OCHLODES SYLVANOIDES(Bd.) 29 Ochlodes ochracea (Brem.) [Japan] 24 NASTRA UHERMINIERI (Latr.) 30 Thoressa varia (Mur.)                          31

Polytremis pellucida (Mur.) [Japan] 16 Pelopidas mathias (Fab.) [Japan] 16 Parnara guttata (Br. & Grey)          16

Reference

3(1) 3(1)

$ (I, II)

3(1)

3(H)

$ (II), $

:d

$ (i, ii)

^(i)

$ (I, II), 9 (I)

$ (i, id 3(i,n) $ (i, ii)

3(1,11) 3 (I, II) 3 (I, II) 3 (I, II) 3d, IT) 3(1,11) 3 (I, ID 3(I,H) 3(1)

Maeki, 1953 Maeki, 1953

Present paper-Present paper Lorkovic, 1941 Federley, 1938 Lorkovic, 1941 Lorkovic, 1941 Lorkovic, Federley, Lorkovic, Lorkovic, de Lesse, 1953 Maeki, 1953 Lorkovic, 1941 Present paper Present paper Present paper Present paper Present paper Present paper Present paper Maeki, 1953

1941 1938 1941 1941

$ (I), 9 (I)            Federley, 1938

3 (I, II), 9 (I, II) Federley, 1938 Lorkovic, 1941 $ (I, II)                    Present paper

$ (I)                         Maeki, unpublished

$ (I, II)                    Present paper

$ (II)                        Maeki, 1953

$ (I)                         Maeki, unpublished

$ (I)                          Maeki, unpublished

$ (I)                          Maeki, 1953

2. MEGATHYMID/E

Megathyminae:

MEGATHYMUS VIOL/E S. k T. 27                    $ (II)                        Present paper

STALLINGSlA MACULOSA (Fr.) 50                    3(H)                        Present paper

ZEgialinae: AGATHYMUS MARI7E (B. &B.) 21                    3 (I, II)                    Present paper

'Table 1, for the Papilionidae, is in Part 1 of this series of papers (Journ. Lepid. Soc. 13: 199; 1960).

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Table 3. CHROMOSOME NUMBERS OF THE PIERID^.

Species

Number (n)

Division

Reference

A. Pierinas:

Anthocaris scolymus Butler EuchJor cardamines (L.)

Euchloe crameri Butler EUCHLOE AU SON WES Lucas

Calias croceus (L.)

COLIAS EURYTHEME Bdv. COLIAS PHILODICE (Godart) COLIAS ALEXANDRA Edw. COLIAS SCUDDERII Reak.

Colias hyale (L.)

Colias eratc (Esper) Colias palceno (L.)

Colias nastes Bdv. Colias hecla Lefebre COLIAS MEADII Edw. ZERENE CESONIA (Stoll) Gonepteryx rhamni (L.)

Gonepteryx mahaguru (Gistel) ANT EOS CLORINDE (Godart) Hebomoia glaucippe (L.) PHCEBIS PHI LEA (Joh.) KRICOGONIA LYSIDE (Godart) Eurema lata (Bdv.) Eurema hecabe (L.) EUREMA PROTERPIA (Fab.) EUREMA [MEXICANA Bdv. or

BOISDUVALIANA F. & F.] EUREMA NICIPPE (Cramer) EUREMA LISA (Bdv. & Lee) APPIAS DRUSILLA (Cramer) A porta cratagi (L.)

9(1)

Aporia hippia (Brem.)

25

5(I,H)

Maeki, 1953, 1959 Federley, 1938 Lorkovic, 194-1 Lorkovic, 1941 Present paper Lorkovic, 1941 Federley, 1942 Present paper Present paper Present paper Present paper Lorkovic, 1941 Federley, 1942 Maeki, 1953, 1959 Federley, 1938, 1942 Maeki, 1959 Federley, 1942 Federley, 1938, 1942 Present paper Present paper Beliajeff, 1930 Federley, 1938 Lorkovic, 1941 Maeki, 1959 Maeki, 1959 Present paper Maeki, 1959 Present paper Present paper Maeki, 1959 Maeki, 1953, 1959 Present paper

Present paper Present paper Present paper Present paper Kernewitz, 1914,1951 Beliajeff, 1930 Federley, 1938 Lorkovic, 1941 Maeki, 1953, 1959 Maeki, 1959

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Journal of the Lepidopterists' Society

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Discussion

Tables 2 and 3 show the chromosome numbers of the 32 species of Hes-perioidea and 48 of Pieridae for which counts have now been recorded. Of the 36 species described in the present paper 34, plus 1 subspecies, are new to cytology and are shown in capitals in the Tables.

Some major groups are notably constant in number. Of the 19 known Pyrginae, 17 have n ~ 30 or 31. The count of 16 for Achalarus toxeus is an extreme variant but can be accounted for by 1 —|— 1 fusions of all but one chromosome (the X-chromosome?). The 9 Hesperiinae shown in Table 2 are diverse, but wt will soon publish accounts of several more species having n — 29, and this seems to be the most usual number for the many small brown temperate-region hesperiines. The 3 n^^Xh Asiatic species appear to

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be in a distinctive phylogenetic line. Their caryotype is remarkably similar to that of A. toxeus. Our finding of n ^= 48 for the hesperiine Asbolis capuci-nus (Lucas), to be reported in detail in our forthcoming supplementary paper, is an extreme departure from the previously published counts for any Hesperiidae.

The chromosomes of the Pierinae are now well enough known to show that on cytological grounds there are two very discrete groups: the Euchloini with 31 as the usual base number and the Pierini with 25-26 as most characteristic. There is no cytological support for the separation of the Colias relatives from the Euchloe relatives. The known American Pieridae have no large variants in number, Ascia monuste and Appias drusilla having only one more chromosome than their relatives. In the known Old World Pierinae two species have large differences from their nearest relations: Pieris brassier (n !— 15 instead of 25 or 26) and Hebomoia glaucippe (n = 17 instead of 31), and we will soon describe an African Leptosia with n — 12. It will be of great interest to work out the numbers for the many American Dismorphiinae, in view of the wide numerical range and the suggestion of polyploidy in the one Palearctic dismorphiine genus, Leptidea.

The family Megathymidae is structurally and biologically divergent and specialized as compared to the Hesperiidae, and the megathymids also prove to be distinctive chromosomally. All 3 known species (and genera) have totally different numbers: w = 21, /z = 27, and n = 50. The latter is the highest known count for any Hesperioidea. Too few of these remarkable Skippers have been worked out for safe generalizations to be made. We intend to give this group special attention, with the help of the Stallings, Turner, and Freeman group of specialists.

The introduced Pieris rape? rapa? is believed to have come to North America from Europe in the 19th Century. Our many counts all agree with those of Beliajeff (1930) and Lorkovic (1941) for eastern European material. Federley (1938) reported n = 26 for both spermatocyte and oocyte divisions in P. raptc from Finland. There is a need for counts from a substantial series of Scandinavian, especially Finnish, P. rnpee to determine howr regular is the haploid number of 26 in that region and whether the 26th element is a normal chromosome or a m-chromosome. (See our remarks on the m-chromosome in our first paper, page 200.) In the Japanese P. rapa* crucivora there is one m-chromosome in addition to the 25 normal chromosomes, and this minute element was found (Maeki, 1959) sometimes among the normal chromosomes and sometimes in the cytoplasm outside the nucleus. If Finnish P. rapec consistently have the m-chromosome there will be a suggestion of phylogenetic affinity with the Japanese race. If there is a 26th normal chromosome there will be the possibility that hybridization experiments will show that the Finnish stock is not true raptr but an unrecognized sibling or a member of a 26-chromosome species such as P. ergane.

A similar situation exists in so-called Pieris napi. Henking (1890), Federley (1938), and Lorkovic (1941) found n ^= 25 in spermatocyte

1960                                        Journal of the Lepidopterists' Society                                              5 5

divisions in European material (Federley also reported n = 23 in a female). We found n = 25 regularly in race macdunnoughii in Colorado. Maeki (1959) showed that the number is 26 consistently in the Japanese "subspecies" nesis and that the extra chromosome is apparently a regular autosome, not a m-chromosome. (His earlier report (1953) of n — 25 was corrected in the later paper.) It is now suggested that nesis is a species distinct from true napi, as is certainly true for the North American virginiensis (n = 26). In the eastern U. S. A. P. virginiensis is mainly more southern than P. napi but has an overlap zone of sympatry in Masachusetts and Vermont and perhaps to the west as well. It is univoltine and very early in its flight, whereas napi is commonly bivoltine and even its first brood is later than the single brood of virginiensis. There is some tendency for foodplant separation, with P. virginiensis larvae always on Dentaria and P. napi on several Cruciferae including Dentaria. Our finding of a chromosome difference is a piece of clinching evidence for the full species status of virginiensis, and the long debate on the question appears to be ended.

The cytological data are not significant in clarifying the status of members of three other complexes we have examined. In these there are no differences in chromosome number. This need not indicate conspecifity (and certainly does not in the second and third complexes), since separate species often have identical haploid numbers. Pieris oecidentalis and P. calyce (see notes above) both have n = 26. In the sibling species group including Eryn-nis baptisice, E. lucilius, and E. persius, all three prove to have n — 31. The eleven known species of Colias, some phenotypically extremely alike, all have n ^= 31. However, the five Colias we have studied have 7 large chromosomes clearly distinguishable in the metaphase plate of the primary spermatocyte division; we found these larger chromosomes still recognizable in the secondary spermatocyte division only in C. alexandra and C. scudderii; possibly this is a significant character.

Summary

1. Chromosome counts are presented for 11 species of Hesperiidae, 3 of Megathymidae, and 22 of Pieridae. All the Hesperiidae are species new to cytology. No Megathymidae had previously been studied. Of the Pieridae, 20 species are likewise new and another count is the first for an American subspecies (Pieris napi macdunnoughii). The cytologically new species are: Achalarus toxeus (Mexico), Chioides catillus (Mexico), Erynnis icelus, ju-venalis, horatius, persius, baptisue, and lucilius (all Connecticut), Grais stigniaticus (Mexico), Ochlodes sylvajioides (Colorado), Nastra rher/ninieri (Connecticut), Megathymus vioUe (Mexico), Stallingsia maculosa (Texas), Agathymus marine (Texas), Euchloe ausonides (Colorado), Colias eury-theme and philodice (Connecticut), C. alexandra, scudderii, and meadii (all Colorado), Zerenc cesonia (Mexico), Anteos clorinde, Phcebis philea, Kri-cogonia lyside, Eurema proterpia, nicippe, and [rnexicana or boisduvaliana] (all Mexico), E. lisa (Connecticut), Appias drusilla (Mexico), Pieris vir-

56                                       Maeki & Remington: Chromosomes                        Vol.14: no.l

giniensis (Massachusetts), Pieris beckerii, occidentalisj and calyce (all Colorado), and Ascia nionustc (Mexico). All these counts are from spermatocyte divisions.

2.   Meiotic divisions are numerous in most adult, flying males of Pieri-da^ and Hesperiidae. Meiosis has almost or entirely ended by the time of eclosion in males of the Megathymidae, the five high mountain Hesperiidae, and the many early spring Erynnis brizo examined by us.

3.  The haploid number tends to be 30 or 31 for Pyrginae, 29 for Hes-periinse, 31 for Euchloini (including the Colias group) and 25-26 for Pier-ini. Some deviant species have been found in each of these groups. The numbers for Megathymidae are widely scattered, the three known species (each in a separate genus) having n = 21, 27, and 50, respectively.

4.   The North American sibling species, Pieris napi and virginiensis, have haploid numbers of 25 and 26, respectively. Japanese supposed P. napi (''subspecies" nesis) has /; = 26. The Japanese P. rape? crucivora has an extra minute element not present in the European and American P. rap a- rapa. In both cases the Japanese forms may actually prove to be separate species rather than subspecies.

5.  Three other complexes of possible or positive sibling species prove to have no difference in number among the similar forms: Pieris occidentalis and calyce; Erynnis persius, baptising, and lucilius; and Colias spp.

6.   The haploid number is only mentioned for Asbolis capucinus, Och-lodes ochracea, Polytrcrnis pellucida, and Pelopidas mathias; descriptions and full records will be reported in later papers.

Acknowledgements

We are again grateful to Dr. and Mrs. Ross B. Dickson of Cuidad Victoria, Mexico, for fine facilities, to P. Sheldon and Eric E. Remington, to Dr. J. R. Turner, and to Don B., Viola Tm and Jack Stallings for field assistance in Mexico, to Eric E. Remington and Roger W. Pease, Jr. for many of the Colorado and Connecticut specimens. Don B. Stallings sent us the living pupae of Stallingsia maculosa. John M. Burns (for Erynnis) and Alexander B. Klots (for Eurema) kindly checked determinations in their special groups. This work was supported in all its parts by a research grant (G 3830) from the U. S. National Science Foundation.

References

Baliajeff, N. K., 1930. Die Chromosomenkomplexe und ihre Beziehung zur Phylogenie bei den Schmetterlingen. Zeitschr. induk. Abstamm. - und Vererbungsl. 54: 369-399.

Doncaster, L., 1912. The chromosomes in the oogenesis and spermatogenesis of Pieris brassiccE, and in the oogenesis of Abraxas grossulariata. Journ. genetics 2: 189-200.

Federley, H., 1938. Chromosomenzahlen finnlandischer Lepidopteren. I. Rhopalocera. Hereditas 24: 397-464, 47 figs.

----......, 1942. Chromosomenzahlen von vier Tagfaltern von ozeanischen Inseln. Hereditas 28: 493-495.

Henking, H., 1890. Untersuchungen iiber die erster Entwicklungsvorgange in den Eiern der Insekten. I. Das Ei von Pieris brassicce L. nebst Bemerkungen iiber Samen und Samenbildung. Zeitschr. iviss. Zool. 49: 503-564, pis.24-26.

1960                                   Journal of the Lepidopietists' Society                                       57

Kernewitz, B., 1914. Uber Spermiogenese bei Lepidopteren. Zool. Auz. 45: 137-139.

............, 1915. Spermiogenese bei Lepidopteren mit besonderer Beriicksichtigung der

Chromosomen. Archiv. Naturgeschichte (A) 81: 1-34, 3 pis., 14 figs.

de Lesse, H., 1953. Formules chromosomiques de Boloria aquilonaris Stichel, B. pales D. et Schiff., B. napcea Hoffm. et quelques autres Lepidopteres Rhopaloceres. Rev. franc, lipid. 14: 24-26, 1 pi., 5 figs.

Lorkovic, Z., 1941. Die Chromosomenzahlen in der Spermatogenese der Tagfalter. Chromosoma 2: 155-191, 13 figs.

Maeki, K., 1953. Chromosome number of some butterflies (Lepidoptera-Rhopalocera). Jap. journ. genetics 28: 6-7, 5 figs.

___....., 1958. On the cytotaxonomical relationship in Leptidea (Lepidoptera-Rhopalocera). Jap. journ. genetics 33: 283-285, 6 figs.

............, 1959. A chromosomal study in fifteen species of the Japanese Pieridae (Lepidoptera-Rhopalocera). Kvuansei Gakuin Univ. annual studies 7: 361-368, 32 figs.

........—., & C. L. Remington, 1960. Studies of the chromosomes of North American

Rhopalocera. I. Papilionidas. Journ. Jepid. soc. 13: 193-203, 3 pis.

Department of Zoology, Ynle University, New Haven, Conn., U. S. A.

A CORRECTION ON HESPERIA PAWNEE IN MICHIGAN

Since the publication of my article entitled, "Observations of Hesperia pawnee in Michigan" (Lepid. news 12: 37-40; 1958), I now realize that a serious error in determination was made. All of the records and observations for H. pawnee Dodge in Michigan referred to in this article should be those of H. ottoe Edw. This error was first called to my attention by Mr. C. Don MacNeill of the California Academy of Sciences after I had sent him specimens determined by me as pawnee. I then shipped to MacNeill, later to Dr. A. W. Lindsey, additional pawnee specimens (my determinations) of both sexes from several localities over a wide range of dates, including the pair originally determined as pawnee by Mr. W. D. Field of the U. S. National Museum, for further examining. In each case the specimens were found to be Hesperia ottoe I Dr. Lindsey stated that my dates of capture, June 19 to August 9, were sufficient to separate the two species, as pawnee flies later than ottoe in the same area. Recently, in checking the left valve of several males in my collection, I found the terminal tooth shorter than the basal tooth — characteristic of ottoe.

It is entirely possible that H. pawnee may occur in Michigan in the same habitat as that of ottoe but during late August and September. In time, I hope to explore this possibility and will report any interesting results.

M. C. Nielsen, 3415 Overlea Dr., Lansing 17, Mich., U. S. A.