Pyrocoelia prolongata Jeng and Lai

Jeng, Ming-Luen, Engel, Michael S. & Yang, Ping-Shih, 2011, Discovery of the female of Pyrocoelia prolongata in Taiwan (Coleoptera, Lampyridae), ZooKeys 116, pp. 49-57 : 49-53

Pyrocoelia prolongata Jeng and Lai

Pyrocoelia prolongata Jeng & Lai, in Jeng et al. 1999b: 358.

Diagnosis.

The female is characterized by the bell-shaped pronotum which resembles that of the male and is one of the diagnostic characters of the species ( Jeng et al. 1999b). No other congeneric species from Taiwan share a similar pronotal morphology and coloration in the female. The temporal and spatial distribution also fits that of Pyrocoelia prolongata .

Description.

Female (Figs 1-7): BL: 15.6 mm; BW: 4.6 mm. Body form elliptical and depressed. Head, antennae, and legs dark brown to black; pronotum translucent gray, with margins and central carina light brown and central disc pink; mesonotum pink, central disc and mesoscutellum dark brown, translucent gray at sides (elytral rudiments); metanotum bronze; abdominal T1 lighter than metanotum and mixed of pink; T2-7 pinkish white, bronze on posterior margins and central line, and translucent gray at lateral margins (Fig. 7A); T8 translucent gray; ventral side pink, brightly so on thorax and pale on abdomen; S8 with a pair of milky white photogenic organs; S8-9 translucent yellowish brown. Head spherical, about 1/3 as broad as pronotum; vertex concave along central line; frons about as broad as clypeus-labrum; antennal sockets widely separated from each other; antenna (Fig. 2) 11-segmented, weakly serrate and rod-like; antennomere 1 largest and 3 slightly smaller than it; clypeus-labrum (Fig. 3) not fused with frons, shell shape; mandibles partially sclerotized, thick in basal 2/3 and slender and somewhat curved at apex; maxillary palpus 4-segmented; labial palpus 3-segmented. Pronotum bell-shape, strongly convex on central disc and weakly so in windows, reflexed at margins; windows on apical 1/3 and divided by central carina. PL/PW = 0.85. Mesonotum as broad as central disc of pronotum, with elytral rudiments abbreviated and round at sides, not extending beyond pronotum; mesoscutel lum transverse, broader than long by 2 times, with apex slightly notched. Metanotum broader than pronotum, transversely elliptical, with a concave central line. Metepisternum fused with metasternum (Fig. 5). Legs (Fig. 4) moderate in width and length, 5th tarsomere slightly longer than preceding tarsomere. Abdomen broadest at T2, T1 about as broad as T3 and diminishing in width accordingly toward apex; T1-8 each with short but clear hind angles; T1-7 with a paler central line; T8 (Fig. 6) transverse and subquadrate, sinuate at sides and central apex. P1-7 folded on inner margins, each bearing a spiracle at center. S8 deeply notched centrally, with a pair of photogenic organs at sides (= PO, Fig. 6, Fig. 7B).

Material examined.

1♀, S. Taiwan: Kaohsiung County (now Kaohsiung City), Yako logging trail (abandoned), 120 º57’ E, 23 º16’ N, 2700m above sea level, 8.VII.2004 around midday, M. Satô leg.; specimen deposited in the collection of the senior author, National Museum of Natural Science, Taiwan.

Sexual dimorphism.

Females differ from males by (generic level differences) 1, having shorter and less serrate antennae, much smaller compound eyes, and smaller palpi; 2, the mesoscutellum as broad as long; 3, the highly abbreviated elytra and absence of hind wings; 4, the fusion of metepisternum and metasternum; 5, having an intact abdominal S1; 6, having the hind angles of abdominal T1-7 not very acute; 7, S8 being deeply emarginate (cf., Jeng et al. 1999b); 8, (remainder are species-level differences) the bronze on the metanotum and abdominal T1; and 9, the narrower dark margins on the pronotum. In contrast to known females of Pyrocoelia , the female of Pyrocoelia prolongata is smaller than its respective males. We are not sure if this is simply individual variation or universal to the species.

Habitat and phenology.

The female was found in a small, shady, and damp dry streambed at the edge of a mixed forest dominant with Taiwan Red False Cypress [ Chamaecyparis formosensis Matsumura ( Cupresaceae )] (Fig. 8A). It stayed on the substrate mixed of gravel and sand under a slate stone (Fig. 8B). An Alishan salamander ( Hynobius arisanensis Maki) was also found in the microhabitat. Only a few species of Lampyrinae such as Diaphanes nubilus Jeng & Lai, Pyrocoelia formosana Olivier, and Pyrocoelia prolongata have ever been recorded from localities at such high elevations in Taiwan ( Jeng et al. 1999a, some of the species denoted as “sp.” at that time). No living male of Pyrocoelia prolongata was found in or around the locality during the 3-day duration of our collecting trip, except for an already dead individual. This suggests that the mating season might have come to an end. At that time, a population of the species in central Taiwan (Anmashan, Taichung County, alt. 2300m) was in a peak season of activity (C.F. Lee, pers. comm.).

Behavioral remarks.

A male of Pyrocoelia formosana collected from the same locality was put together with the female in a transparent plastic container to observe their interaction. At first the male did not show interest in the female. Later it attempted to copulate with the female but failed due to the female’s resistance. They eventually copulated after one day of captivity. The male perished soon after copulation, while the female survived the following week and laid three or four eggs before she died. All eggs failed to hatch and decomposed. The female glowed in darkness via a pair of photogenic organs on abdominal sternite 8. When wagging a finger around the female’s head in a dusky environment, the female responded by powerfully raising her abdomen vertically to the body axis then laid down. It was found to be a one-to-one response after several repetitions. Apparently the female can detect the nearby moving subject and the action could be an intimidation to predators.

Key to the females of Pyrocoelia species of Taiwan