The text below is grayed out because it is not intended to be read. It is a necessarily imperfect OCR of the original and is only used by a search engine.
266
Journal of the Lepidopterists' Society
Meigen, J. W. 1832. Systematische Beschreibung der europaischen Schmetterlinge.
Aachen, vol. 3. Treitschke, F. 1826. Die Schmetterlinge von Europa (Fortsetzung des Ochsen-
heimer'schen Werks). Leipzig, vol. 5 (pt. 3).
Editor's Note: Mr. Steyskal's paper is an illuminating one and we are happy to have it for the Journal. I cannot see, however, how Article 11(b) would override Article 29(a) which states: "—if the name of a type-genus—is a Greek or Latin word—the stem is found by deleting the case-ending of the appropriate genitive singular." From a puristic standpoint, the subfamily name should be the Heliothentmae. This, as well as the matter of the gender of Heliothis as suggested by Mr. Steyskal, should be submitted to the Commission for a ruling.
VARIATION IN LARVAL COLOUR PATTERNS OF ITAME RIBEARIA (GEOMETRIDAE)
W. C. McGuFFIN AND K. BoLTE
Forestry Branch, Canada Department of the Environment, Ottawa, Ontario
Some geometrid larvae have distinctive colour patterns, others do not; some species of Itame are good examples of the former (McGuffin 1956). Dugdale (1961) has shown the importance of infraspecific variation in colour patterns and has suggested that such variation could offset the value of coloration for the separation of species. An opportunity to examine infraspecific variation came in 1968 when a colony of Itame nbearia (Fitch) was located on an ornamental species of Ribes at Bells Corners, Ontario.
Of the larvae collected the following were preserved in 70% ethyl alcohol: 1 in third instar, 33 in fourth instar and 17 in fifth instar. A small number was reared; these provided head capsules in second, third, and fourth instars and information on changes in colour pattern as the larvae matured.
In the first instar, the head capsule is black; the body is light grey with a black area surrounding the base of each D seta, a subdorsal grey stripe of irregular width, and setae L, SV, and V each with a patch of grey at the base.
In the second instar, the head (3 examined) is light brown with five black patches, one as a bar at base of clypeus and two on each parietal
Volume 25, Number 4
267
lobe, one in ocellar area and one on the upper part of the lobe bearing setae P and L (Fig. 1); the third abdominal segment (A3), which is typical of the anterior abdominal segments in this species, is light grey, suffused with yellow and with black or dark grey patch at base of each seta, sometimes with grey line connecting patches at base of SD1.
In the third instar, the head (3 examined) is much the same as that in second instar (Fig. 2); A3 is much the same as in second instar with a large spot bearing setae SD1 and a small spot posterior to former (Fig. 3).
In the fourth instar, five different colour patterns of the head were noted in an examination of 33 larvae and five head capsules. The basic pattern of five spots is present with variation in size of the spots on the parietal lobe. In 17 specimens the patch on the upper part of the lobe included the base of seta A3; in 3 of the 17 the ocellar patch did not include seta Al (Fig. 4) but in the remainder it did (Fig. 5). In 16 specimens seta A3 was not included in the patch on the upper parietal lobe (Fig. 7) and in 7 of these the ocellar patch included seta Al (Fig. 6). In one specimen the ocellar patch included seta A2 as well as seta Al (Fig. 8). On A3 only two distinctly different patterns were noted. The patches bearing setae SV1 and SV3 were separate (Fig. 9) in 16 larvae and connected in 9 larvae (Fig. 10).
In the head capsule of the fifth instar the upper parietal patch was similar in all 17 specimens (Fig. 19) but the ocellar patch in one specimen (Fig. 20) extended out to include seta Al. Eight variations in the colour pattern of A3 have been illustrated (Figs. 11-18) and others have been seen. In all, the subventral stripe is of uneven width and broken or almost broken between setae L3 and SV4 on the one hand and setae SV1 and SV3 on the other.
Discussion
This study suggests that the colour pattern of A3 will distinguish mature (fifth-instar) larvae of I. ribearia from those of I. occiduaria (Packard), I. evagaria (Hulst) and I. andersoni Swett: the subventral stripe is broken in I. ribearia but apparently continuous in the other species (Mc-Guffin 1956). The colour pattern of the head aids in this separation but by itself is too variable to define the species. In Deilinia and Drepanu-latrix (McGuffin 1969) the colour patterns of the head were of more value in separating species than were the colour patterns of the anterior abdominal segments.
The colour pattern of the head develops from a unicolorous black in the first instar to a five-spotted one in the second and later ins tars. On the other hand the pattern on A3 changes gradually from the first to the last instar.
268
Journal of the Lepidopterists' Society
Figs. 1-10. Colour patterns of head and third abdominal segment (A3) of Itame rihearia (Fitch). 1, Second-instar head; 2, third-instar head; 3, third-instar A3; 4-8, fourth-instar head; 9-10, fourth-instar A3.
Volume 25, Number 4
269
Figs. 11-18. Colour patterns of fifth-instar A3 of Itame ribearia (Fitch)
270 Journal of the Lepidopterists' Society
Figs. 19-20. Colour patterns of fifth-instar head of Itame ribearia (Fitch).
Most of the dark patches on the body of Itame ribearia larvae surround setae. However, there is one patch with no seta; this patch lies between setae LI and D2 on the anterior abdominal segments. It is near the position of seta SDX2 of Galenara lallata (Hulst) (McGuffin 1967) and other genera of the Melanolophiini. The dark patch on I. ribearia may have no relation to the extra seta in the Melanolophiini but its presence provokes speculations.
Literature Cited
Dug dale, J. S. 1961. Larval characters of taxonomic significance of New Zealand
Ennomines (Lepidoptera: Geometridae). Trans. R. Soc. N. Z. Zool. 1: 215-233. McGuffin, W. C. 1956. Some larvae of the genus Itame Hiibner (Lepidoptera:
Geometridae). Can. Ent. 88: 6-16. McGuffin, W. C. 1967. Immature stages of some Lepidoptera of Durango,
Mexico. Can, Ent. 99: 1215-1229. McGuffin, W. C. 1969. Larval head capsule characters for specific identification
in Deilinia and Drepanulatrix (Lepidoptera: Geometridae),, Can. Ent. 101: 1228-
1231.