Pygoluciola qingyu, Fu, Xin Hua & Ballantyne, Lesley, 2008

Fu, Xin Hua & Ballantyne, Lesley, 2008, Taxonomy and behaviour of lucioline fireflies (Coleoptera: Lampyridae: Luciolinae) with redefinition and new species of Pygoluciola Wittmer from mainland China and review of Luciola LaPorte, Zootaxa 1733, pp. 1-44 : 9-13

Pygoluciola qingyu new species

Figs 11 , 15 , 17–18 , 21–40

Types. Holotype, male. Yuan An County, 700 m, Yi Chang City, Hubei Province, China, July 27, 2005, X. H. Fu (Beijing, NHMHAU). Paratypes. 21 male, 9 females, 5 larvae, same data as above; 6 male, 4 females, 4 larvae, Yan Jing Po Village, 532 m, E Mei Mountain, Sichuan Province, China, July 8 2006, X. H Fu (Beijing, NHMHAU).

Etymology. Qingyu is a Chinese name meaning universe of starry skies and the specific name is considered here as a noun in apposition (Article 34.2.1 ICZN). The luminescent pattern in the research area suggests a starry sky. Larvae on the road surface and/or lower rocks emit a long continuous glow while the male and female adults on the overhanging grass flash (males at times synchronously). Because of the potential for tourism in China Fu has given this species a common Chinese name ‘ qingyu ying’ firefly.

Diagnosis. Distinguished from other Pygoluciola species in lacking an elongate narrow MPP which curves dorsally and a similar median prolongation of T8 curving ventrally, and by its distinctive colouration of pale pronotum with dark markings and very dark elytra (other Pygoluciola are light brown dorsally sometimes with elytral apices dark). Superficially similar to and distinguished from certain Chinese Luciola , which have dark pronotal markings and uniformly dark elytra and rounded posterior margin to V7: L. curtithorax Pic has a single median dark pronotal mark, widening anteriorly, very reddish pink pronotal colour, an aedeagal pattern similar to Luciola italica and L. satoi Jeng et al. (Jeng et al. 2003b, Fig. 21 ) where inner ventral margins of lateral lobes bear elongate narrow projections; the macropterous female is coloured like the male; L. filiformis Olivier has the median dark pronotal area extending across more than half of the anterior margin, brachelytral female, larva with laterally explanate dorsal plates which carry orange and black longitudinal stripes ( Chen, 2003:170–172; Jeng pers comm) Similar to Luciola cerata , distinguished by the uniform pronotal colour in cerata , the shape of the posterior margin and posterolateral corners of T8, the shape of the aedeagal sheath sternite, and the extent of the lateral arms of the sheath tergite; LL lack inner hairy projections; basal piece in 2 well sclerotised and distinct halves. Dorsal colour pattern very like that of Luciola davidis Olivier (type not located) and the decision to erect a new species is discussed in the Remarks section. Females macropterous, coloured as for male except for the LO segments, with strong anteriorly directed hooks in the sides of the bursa. Larvae dorsally almost black, heavily sclerotised, lateral margins project and cover the laterotergites but are not narrowly explanate and the posterior margins of all but the terminal tergite bear 4 rounded projections; mandibles with 2 strong curved and apically pointed teeth on their inner basal margin.

Male. 10.3– 13.6 mm long. Colour. Pronotum orange yellow, with median aggregation of pinkish white fat body; semitransparent anterior and posterior margins devoid of fat body; disc with 2 moderately dark brown spots and 2 more lateral paler brown areas ( Fig. 13). MN pinkish white, MS white. Elytra black. Head, including labrum and antennae (except for brown FS 8 and 9) very dark brown almost black; apical segment of maxillary palpi paler brown and of labial palpi yellowish. Ventral aspect of pro and mesothorax yellow, metasternum brown, metapleural plates yellow. Front legs with pale brown coxae, trochanters and basal ¼ of femora, remainder of front legs very dark brown; middle legs coloured as for front legs except basal ¾ of femora is pale brown; hind legs mainly pale brown except for dark brown anterior face of coxae, extreme apex of femora and all of tibiae and tarsi. Abdomen ( Figs 11 , 15 ) with white LO occupying almost all of V 6 and 7 except for a very narrow clear band around lateral and posterior margins; basal ventrites mid brown, lateral areas paler with irregular light brown markings; T7 and 8 pale yellowish brown semi transparent, remainder of tergites light brown and semitransparent; dorsally reflexed margins of V 6 and 7 white, of remaining ventrites light brown. Pronotum ( Fig. 13): 1.5–2.1 mm long; 3–3.9 mm wide; width/length 2.0; 1/7 as long as whole body; width across posterior margin subequal to width across elytral humeri; median anterior margin rounded and not projecting beyond the anterolateral corners which are angulate, angle acute; lateral margins diverging along their length with no sinuousity at mid point; posterolateral corners rounded, angle acute, angle subtended obliquely with median line of the pronotum, and projecting beyond posterior margin; hypomeron flattened only in posterior half; dorsal surface mainly smooth, gently convex, with median sulcus moderately depressed in posterior half; posterolateral area lacking irregular small low tubercles; punctation small dense, contiguous or separated by width of a puncture in all areas including the lateral areas. Elytra: 8.8 – 11.5 mm long; subparallel-sided for approximately 2/3 their length with some convergence of lateral margins in posterior 1/3; closed elytra contiguous along almost all their length. Head: GHW slightly less than width across hypomera so resting head retracted partially within prothoracic cavity but due to the midanterior margin of the pronotum not projecting forwards, head still moderately exposed from above ( Fig. 13); shallowly depressed between eyes; GHW 1.8–2.1 mm; SIW 0.3–0.8 mm; labrum small semicircular reaching to inner edges of mandibular bases; ASD subequal to ASW. Apical segment of labial palpi laterally flattened, of the form of a wide isosceles triangle, with longer inner edge bearing slender fingerlike projections (4 on each palp); apical segment of maxillary palp ovoid, longer than wide and as long as apical segment of labial palpi, apex rounded. Antennal length subequal to 2 × GHW, FS subequal in length and apical FS slightly narrower than remainder. Legs: femora and tibiae straight, neither swollen or curved. Abdomen: ( Fig. 11 ): LO occupying all of V7 except for a narrow margin that extends all around this segment except across the anterior margin; MPP barely defined, very short. T7: wider than long, not strongly sclerotised, lateral areas depressed. T8 ( Figs 11 , 15 ): anterior margin of T8 bifurcated into two elongate narrow apically rounded projections which are subparallel, not strongly expanded in dorsoventral plane. Aedeagal sheath ( Fig. 17 ): about 3.5 times as long as wide; anterior 7/10 of sternite of sheath elongate, symmetrical and narrow, expanding in posterior 3/10 to a symmetrical oval area which is about as wide as long, and terminated along its posterior margin by paired hairy, apically rounded projections; median dorsal surface with an elongate slender ridge terminating before the posterior hairy lobes in a narrow transverse line; sternite slightly longer than sheath tergite; tergite of sheath projecting at sides beyond lateral margins of sternite, with long lateral well sclerotised arms reaching forward and well to sides of sternite, articulating with it at its sides in its anterior 1/3 and appearing to extend along the sides of sheath sternite to its anterior tip; sheath tergite with anterior margin broadly emarginate, posterior margin truncate, and bearing a transverse narrow darker band just behind median dorsal margin. Aedeagus ( Fig. 18 ): Length/width 3; width across LL at base/ML 2/1; LL taper posteriorly along their outer margins; aedeagus narrower across its posterior 1/3 than across its anterior 1/3; appearing symmetrical from below except for 2 distinct and well sclerotised halves of basal piece not sitting evenly above the lateral and median lobes; base of LL slightly asymmetrical; ML tapering evenly towards bluntly rounded apex; ML about 3/4 as long as LL, with V shaped emargination at base, and articulating with the inner surface of the bases of the LL (A in Fig. 18 ); LL visible to either side of ML from below, separate along about half their length dorsally, margins tapering to rounded, close but not contiguous apices; basal 7/10 of LL darker, apical 3/10 pale and fleshy; inner area of LL along mid-dorsal line narrowly sclerotised (B in Fig. 18 ) and continuing along inner margins of separated LL for about half the (separated) LL length (C in Fig. 18 ), where another sclerotised ridge arising on ventral surface runs obliquely forward towards outer margins of LL (D in Fig. 18 ); junction of these two areas on inner margin of each LL appearing slightly hook–like (arrow in figure); apical areas of LL posterior to ridge ‘D’ narrow, pale and with an elongate brush of hairs along inner ventral surface; lacking narrow leaf like fleshy hairy lobes on ventral surface of LL posterior to ridges D.

Female. 11.0– 12.3 mm long, 3.5–4.2 mm wide across widest point of closed elytra; width/length 0.3; macropterous and observed in flight; colour similar to that of male except for black FS 7–9, white LO in V6 only and V 7 and 8 pale brown; abdominal tergites brown except for pale brown semitransparent T7 and 8. Similar to male with these exceptions: Pronotum: 1.7–2.4 mm long, 3.4–4.1 mm wide; 1/5 as long as whole body length; width/length 1.7–2; median anterior margin not produced, remainder of pronotum as described for male. Elytra 9–10.1 mm long. Lateral margins slightly divergent in anterior 1/5, sub-parallel- sided for next 2/5 and slightly convergent in posterior 1/5. Head of winged female form: GHW 1.8–2.0 mm (about half as wide as greatest pronotal width); GHW <width across hypomera and head retracted into prothoracic cavity in repose but the median anterior margin of the pronotum not rounded thus the head visible from above even when retracted. SIW 0.5 mm; ASD subequal to ASW; barely depressed between eyes. LO occupying whole of V6 only; V7 broad, not heavily sclerotised, lacking external developments (transverse ridge, lateral mounds) except for a possible median longitudinal depression; posterior margin of V7 smoothly and shallowly emarginate; posterolateral corners apically rounded, about as long as wide, projecting posteriorly beyond the median posterior margin of V7 by about their width; median posterior margin of V8 narrowly emarginate; V 8 with an elongate slender anteromedian prolongation of similar length to posterior expanded portion; this prolongation darker than remainder and only partially articulated with posterior area. Genitalia ( Fig. 21 ): valvifers elongate slender 3 × as long as coxites, diverging slightly in posterior 1/3 of their length; posterior portion of coxites elongate slender as long as anterior wider portion, tipped with hairy elongate styli. Reproductive system ( Fig. 22): similar to that described ( Ballantyne and Lambkin 2001, 2006); bursa hooks present, large (0.8 mm long), with three free points: the longest inclining posteriorly, the shortest towards the inner cavity of the bursa, and the other anteriorly.

Larva. ( Figs 2–5, 23–40 ). This description was prepared from 5 final instar larvae collected by Fu. 12.0 mm long. Active larvae with their dorsal plates inclining toward mid line, thus slightly tent like. Dorsal surface fairly smooth covered with fine hairs sitting in small pale areas of the cuticle (these pale areas only clearly visible microscopically and covering the anterior 1/3 or less, and the sides of the median line of each of segments 2–12 and narrowly anteriorly on segment 13). Dorsal surface with minute bluntly ending projections lining the sides of median line and anterior areas of each tergum and also the laterally reflexed margins. Most of the venter of the thorax pale with dark bases to coxae and dark median plate beneath head capsule. Abdomen: most ventral plates dark brown; median sternal plates pale semitransparent and slightly pink because of underlying fat body; sternal plate of segment 8 semitransparent and pale. Protergum longer than wide, anterior margin bluntly rounded and containing retracted head beneath; depressions of dorsal surface indicated ( Figs 33–36 ); lateral margins diverging a little posteriorly, somewhat less so in posterior half; ventral surface not differentiated apart from well sclerotised dark plate lying beneath retracted head. Remaining terga as figured, thoracic terga 2 and 3 ( Figs 37–38 ) shorter than protergum and subequal in length and longer than abdominal terga 1–9 ( Fig. 40 ), and subequal in length to tergum 10 ( Fig. 39 ). Pygopodia retracted thus only the dark coloured ventral plate of each set visible. Posterolateral corners of terminal tergum obliquely truncate ( Fig. 39 ).

Behaviour and Ecology. A large population of P. qingyu sp. n. larvae occurs along the very wet environment of the river side in Yuan An County, Yi Chang City, Hubei Province ( Fig. 1 ). Rocks along the river are covered by thick grasses and overhanging vegetation. The area abounds in aquatic snails, bodies of insects, which attract ants to feed, and other small invertebrates.

P. qingyu larvae prey on two ant species, Odontomachus monticola Emery and Monomorium chinense Santsch. The larva approaches a foraging ant from the side, turns its head towards the ant, and attacks it head on, impaling it between the ant’s large mandibles ( Figs 3–4 ). Larvae grasp the struggling ant with legs 1 and 2 and crawl backwards dragging it. When struggling ceases the larva commences to feed. Larvae were observed attacking a perched mosquito ( Culex pipiens pallens Coquillett ) and will feed on the dead bodies of insects, earthworms, and occasionally aquatic snails.

Before moulting, larvae attach the end of their body to an overhanging surface using their pygopodia, and hang in the manner of most lepidopterous pupae ( Fig. 5 ). No observation on pupation was made.

Apart from one firefly which was caught in a spider’s web, no obvious predator of the fireflies was observed. Adults take water but appear to take no solid food.

Larvae can survive under water for short periods. After 24 hours immersion in non oxygenated water all larvae were crawling on the surface of the vials. After 36 h immersion, all larvae lay inert on their backs, but when removed from the water 17 of 20 larvae revived. After immersion in oxygenated water, eight larvae were alive and active after 48 h and four larvae alive after 60 h.

Luminous behaviour. Larvae produce glows of 2.5 to 4 seconds flash duration at random intervals. The light spectrum of male P. qingyu is between 508–699 nm, with the peak emitted wavelength (λ max) at 580 nm thus producing a yellow flash. The female spectrum is between 502- 719 nm, with the peak emitted wavelength (λ max) at 565 nm producing a greenish yellow flash ( Fig. 7 ).

During the day adults rest under leaves of overhanging grasses. About 20 min after sunset, perched males and females began to flash en mass, with adult males synchronising their 0.12 sec flash. Fu (unpublished data) recorded the mass flashing and selected two randomly flashing individuals, and found the same flash rate (8 flashes/s) between individual males ( Fig. 9). Female flashing was non-synchronous though their flashes had a duration 0.6 s, interflash interval of 0.2 s and thus a period of 0.8 s ( Fig. 10). When males flew to perched and flashing females, they crawled above them and directed their terminal abdomen and flashes into the females’eyes. Males mounted and copulated when females accepted them ( Fig. 6 ). Forty minutes after sunset, the flashing activity of males reached its peak and then decreased gradually. Ninety minutes after sunset the flash activity ceased, but if ‘induced’ with a torch light producing a yellow flash (about 0.5-1 s duration, 0.5 s interval), the perched males began to synchronize again, flashing brightly for 10 to 20 s.

Discussion.

Taxonomic considerations.The similarity of this species to the description of Luciola davidis by Olivier (1895) is noted. The type was not located at MHNP by either Jeng or Ballantyne (separately), and Jeng (pers. com.) felt that the most appropriate method of dealing with this species, which has associated females and larvae and considerable behavioural information, was to erect a new species. However, the decision to assign it to the genus Pygoluciola , and thus modify the existing definition of Pygoluciola ( Ballantyne & Lambkin, 2001, 2006) is based on an as yet unpublished phylogenetic analysis (Ballantyne and Lambkin work in progress).

Aquatic or semiaquatic? While terrestrial Luciola species are known almost world wide ( McDermott, 1966), aquatic Luciola are known mainly from Asia ( Jeng et al., 2003a; Fu et al., 2005, 2006). Aquatic larvae must live in water and most have gills along the side of the abdomen ( Jeng et al., 2003a; Ballantyne & Menayah, 2002). Luciola substriata Gorham is unusual as early stage larvae have gills while later stages are metapneustic and protrude the end of the body above the water to respire ( Fu et al. 2005; Jeng et al. 2003a). Semi (facultatively) aquatic fireflies ( Ohba & Goto, 1991) have behaviour similar to P. q i n g y u. Buschman (1984) found some larvae survive immersion for up to 12 days, but also that they entered the water to prey on aquatic snails which they then drag above the water for feeding. Such larvae lack gills, as does P. qingyu larvae, which can remain immersed for long periods in well oxygenated water, have a hardened dorsal exoskeleton and no obvious adaptations to the aquatic mode of life. The pygopodia (while not unique to this species) allow the larvae to cling to the rocks and not be swept away by the current.

Feeding behaviour. Many larvae prey on snails and slugs, impaling their prey with channelled pointed mandibles along which a toxin is injected. Snails are usually immobile after having been bitten and may not withdraw into their shells (Fu obs; Ballantyne obs). Once a P. q i n g y u larva has bitten an ant, its head is between the two enormous ant mandibles which appear to be disengaged, although the ant continues to struggle. Feeding only commences once the ant ceases to struggle. The basal teeth on the larval mandibles which ensure a tight grip are not exclusive to P. qingyu and occur also in Pyrocoelia larvae (Fu obs), which have been observed feeding on snails (Fu obs). The method of a potentially hazardous front on attack and fairly rapid immobilisation is thus far an unusual feature of this species only.

Larvae may prey on earthworms ( Ohba et al., 1996a; Ohba & Sim, 2000; Fu obs) and millipedes ( Ohba et al., 1996b) but apart from laboratory reared larvae of Luciola sp. (? chinensis ) feeding on termites (Fu obs) no Asian firefly larvae were known to prey on insects (unlike the African L. discicollis LaPorte [ Kaufmann, 1965]). P. qingyu larvae feed on living and dead insects, earthworms and other dead invertebrates.

Synchronous flashing. Considerable potential exists for such a display to attract tourism. The spectacular phenomenon of synchronous flashing was known only in tropical areas of Southeast Asia such as Malaysia, Thailand, Singapore and New Guinea ( Ohba and Sim 1994; Ohba & Wong 2004; Ballantyne & Menayah 2000). In Malaysia at the Selangor River Pteroptyx tener Olivier is a tourist drawcard ( Ballantyne & Menayah 2000). In New Guinea the tourist potential is not as well appreciated. Atyphella obsoleta Olivier engages in flashing displays in the Botanic Gardens at Lae ( Ballantyne 1968). Pteroptyx effulgens Ballantyne displays in a most spectacular fashion, but many localities are known only to local farmers and interested entomologists (Ohba pers. comm.).

In China, no synchronously flashing firefly was known prior to the present study. Males of P. qingyu can be stimulated using a weak yellow torch light to flash synchronously even after the courtship activity has ended for the night.

Figures

FIGURE 1. Larval habitat (Note the protruding rocks, the grasses overhanging from the top of rocks, and the surface of road near the rocks which is covered with water).

FIGURE 3. Larva: attacking the head of ant Odontomachus haemactadus. Scale bar = 5 mm.

FIGURE 5. Larva: moulting, having attached the pygypodia to the low part of rock. Scale bar = 5 mm.

FIGURE 6. Adult male and female: in copulation (male to right). Scale bar = 0.5 cm.

FIGURE 7. Adult male and female: Light spectrum of each sex (M = male; F = female).

FIGURE 11. Adult male: abdomen and elytra, ventral (anterior end to right).

FIGURES 17. Adult male: aedeagal sheath ventral (left) and dorsal.

FIGURES 18, 20. Adult male: aedeagus from left to right dorsal, ventral, and left lateral.

FIGURE 21. Adult female: genitalia ventral (anterior end to right of page).

FIGURE 23. Larva: outline dorsal surface only.

FIGURE 24. Larva: head, semidiagrammatic, dorsal surface, antennae and mandibles only. M mandible; A 1 - A 3 antennal segments 1 - 3; S stemmata.

FIGURE 25. Larva: head anterior half dorsal. Scale bar = 0.43 mm. A, antenna; AM, antennal membrane; S, stemmata; M, mandible.

FIGURE 26. Larva: head, anterior half, ventral. Scale bar = 0.5 mm. L, lacinia; LP, labial palp; MP, maxillary palp; PM, prementum; POM, postmentum.

FIGURE 27. Larva: mandibles dorsal. Scale bar = 200 μm. M, mandible.

FIGURE 28. Larva: apical segments of left antenna from below. Scale bar = 150 μm. A 1 - A 3, antennal segments 1 - 3; SC, sense cone antenna.

FIGURE 29. Larva: left antenna detail segment 3 and sense cone. Scale bar = 43 μm. A 3, antennal segment 3; SC, sense cone.

FIGURE 30. Larva: ventrolateral view apical half of both mandibles showing inner teeth of left mandible. Scale bar = 136 μm. M mandible.

FIGURE 31. Larva: dorsolateral view, apices maxillary and labial palpi. Scale bar = 120 μm. LA, lacinia; LP, labial palp; MP, maxillary palp.

FIGURE 32. as for 31, ventrolateral view, R side only. Scale bar = 120 μm. MP, maxillary palp.

FIGURE 33. Larva: protergum (anterior end to top right).

FIGURE 34. detail 33, mid line. Scale bar = 120 Μm.

FIGURE 35. detail 33, anterior margin. Scale bar = 231 Μm.

FIGURE 36. detail 33, posterior margin (anterior end to bottom left). Scale bar = 0.6 mm.

FIGURE 37. Larva: mesotergum (anterior end to bottom left). Scale bar = 0.86 mm.

FIGURE 38. detail 37 mid line. Scale bar = 0.27 mm.

FIGURE 39. Larva: terminal tergum (anterior end to bottom left). Scale bar = 0.5 mm.

FIGURE 40. Larva: abdominal terga. Scale bar = 0.75 mm.

FIGURE 15, 16. Adult male: ventral aspect tergite 8.