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Volume 44, Number 2
93
Journal of the Lepidopterists' Society 44(2), 1990, 93-94
LARVAL MANDIBLE OF CARGIDA PYRRHA (NOTODONTIDAE)
Additional key words: morphology, retinaculum, Costa Rica.
The mandible of Cargida pyrrha (Druce) was characterized as having three large, truncated retinacula based on last-instar larvae collected near the end of their feeding phase (Godfrey, G. L. 1984, J. Lepid. Soc. 32:88-91). The mandibular specimens appeared to be worn, but the absence of other collections of larval C. pyrrha prevented further study. D. H. Janzen (pers. comm.) suggested that the truncated retinacula of C. pyrrha may be used to crush excised leaf tissue. A refined picture of the mandible's functional morphology became possible with the collection of a third-instar larva of C. pyrrha in Canon del Tigre, Santa Rosa National Park, now part of Guanacaste National Park, Guanacaste Province, Costa Rica, on 10 June 1986. The sharpness of the edges on the retinacula and distal teeth indicated that the mandibles were unworn. As expected, the distal teeth are more angulate than earlier described. Especially noteworthy is a very distinct, dorsally directed, angular extension of the dorsalmost retinaculum (Fig. 1). When the mandible is fully closed, this extension is directed posteriorad. This suggests that, in addition to having a possible crushing function, the dorsalmost retinaculum may also help move food material toward the pharynx during mandibular adduction. In an unworn state, the last-instar mandible should be morphologically and functionally similar. This assumption partially is supported by the larval mandible of Crinodes besckei Hiibner, which also has distinct retinacula that are similar morphologically from the third through fifth (=final) instars (Godfrey, G. L., J. S. Miller & D. J. Carter 1990, J. New York Entomol.
Fig. 1. Scanning electron micrograph showing medial view of third-instar larval mandible of Cargida pyrrha (scale bar = 0.25 mm). Pointer shows dorsalmost retinaculum.
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Journal of the Lepidopterists' Society
Soc. 97:172-197). The observed third-instar larva of Cargida pyrrha was found clinging to a rock in the middle of a steep, eroded jeep trail, apparently having been disloged or washed there from its host by torrential rains that recently had ended. Attempts to locate feeding larvae of C. pyrrha in the area were futile, so no additional specimens or hostplant information were gathered.
Gratitude is owed the Servicio de Parques Nacionales de Costa Rica for permission to work at Santa Rosa National Park. D. E. Dockter assisted with the scanning electron microscopy. Financial support came from the University of Illinois Research Board, Herbert Holdsworth Ross Memorial Fund and Illinois Agricultural Experiment Station Project 12-361 (Biosystematics Insects).
G. L. Godfrey, Center for Biodiversity, Illinois Natural History Survey, 607 E. Peabody Drive, Champaign, Illinois 61820.
Received for publication 26 December 1989; revised and accepted 21 February 1990.
Journal of the Lepidopterists' Society 44(2), 1990, 94-95
DIETARY BREADTH IN EUPHYDRYAS GILLETTII (NYMPHALIDAE) Additional key words: Lonicera, Pedicularis, Valeriana, Veronica, hostplants.
Ever since J. A. Comstock (1940, Bull. S. Calif. Acad. Sci. 39:111-113) reported its hostplant to be Lonicera involucrata (Rich.) Banks (Caprifoliaceae), Euphydryas gillettii (Barnes) has been thought to be monophagous. My observations over the past decade, however, have revealed oviposition by E. gillettii on several additional plant species. Here I report these observations, along with an evaluation of dietary breadth of this butterfly in light of hostplant choice in other Euphydryas.
These reports are based on observed oviposition or discovery of egg masses on the plants, not simply on larval feeding; thus, they differ from other reported hostplant records for E. gillettii, such as those in J. A. Scott (1986, The butterflies of North America, Stanford Univ. Press, 583 pp.), which include records of feeding by wandering post-diapause larvae. Although the following new hostplants differ in growth form (shrub or perennial), all are in families that possess iridoid glycosides (M. D. Bowers, pers. comm.). These compounds are sequestered, producing unpalatability (Bowers, M. D. 1981, Evolution 35:367-375; Gardner, D. R. & F. R. Stermitz 1988, J. Chem. Ecol. 14:2147-2168), and also may function as feeding and ovipositional stimulants. The additional records are the following. E. H. Williams and M. D. Bowers (1987, Am. Midi. Nat. 118:153-161) reported infrequent oviposition (1-4% of all egg masses) in a Wyoming population on Valeriana occidentalis Heller (Valerianaceae). A field survey of E. gillettii populations (Williams, E. H. 1988, J. Lepid. Soc. 42:37-45) revealed extensive use in an Idaho population of Pedicularis groenlandica Retz. (Scrophulariaceae) and Lonicera caerulea L., in addition to L. involucrata. Furthermore, an alpine population of E. gillettii oviposits on Veronica worm-skjoldii Roem. & Schult. (Scrophulariaceae) (letter, C. F. Gillette, 14 Feb 1985).
Feeding experiments have shown that larvae survive and grow well on the additional hostplants. Williams and Bowers (op. cit.) found no significant difference in survivorship and growth of larvae on V. occidentalis and the usual host L. involucrata. Similar experiments showed no difference among L. involucrata, L. caerulea, and P. groenlandica as hostplants for larvae from the population that uses all three (Table 1). The use of alternative hostplants is therefore not simply ovipositional error.
Although individual populations are locally specialized, all other Euphydryas species whose basic ecology is known, including Eurasian as well as North American species, oviposit on several plant species each. The minimum number of plant genera (species)