Chetoneura shennonggongensis, Amorim & Niu

Amorim, Dalton De Souza & Clarke, Arthur K, 2008, Chetoneura shennonggongensis, a new species of cave – dwelling Keroplatini from China (Diptera: Keroplatidae), with a discussion of the position of Chetoneura, Zootaxa 1716, pp. 59-68 : 60-66

Chetoneura shennonggongensis, Amorim & Niu , sp.n.

Diagnosis. Long fusion of M1 to Rs. Male gonostyle only with setae distally, tergite 9 wide anteriorly.

Material examined. Holotype male, limestone cave: Shennong Gong, near Pan Ling village, Huangtian Mountain, northeast Jiangxi (Province), Wannian Xian (County), East CHINA. GPS co–ordinates: 117° 15’ 00.69" E, 28° 42’ 45.17" N; elevation, approximately 370 m. Larvae reared in laboratory by Xuezhen Li; adult (holotype) male emerged July 20, 2006. Paratypes, same data: 2 males (emerged June 6, 2006), 2 females (emerged August 1 and 23, 2006) and 4 larvae (fixed in 70% alcohol on June 6, 2006). Holotype and paratypes in the Museu de Zoologia da Universidade de São Paulo, Brazil.

Description.

Male. Head. Antenna brown, placed on a short protuberance ( Figs. 1–3 ); 14 flagellomeres, first flagellomere about twice the second, flagellum fairly compressed, with microtrichia, small setae and scattered sensilla laterally and ventrally, longer setae dorsally; scape and pedicel shorter than flagellomeres. Two ocelli, medially on the vertex. Eyes normally developed, with ommatidia hairs. Frons and clypeus brown, setose, clypeus projected. Palpus reduced to single small palpifer and a rounded distal segment with a few setae. Occiput dark brown, yellow brown close to the eyes ( Fig. 4 ).

Thorax. Scutum brown, lighter at the borders, scutellum dark brown; scutum strongly arched posteriorly, uniformly setose ( Fig. 4 ). Proepisternum and proepimeron brown, anepisternum brown, katepisternum, mesepimeron, and metepisternum light brown; laterotergite and mediotergite whitish, weakly sclerotized Anepisternum with about nine setae dorsally, laterotergite, katepisternum, and mesepimeron bare; no postspiracular setae; laterotergito and mediotergite rather weakly sclerotized, mediotergite with a group of about 20 setae medially, the triangular subscutellar membranous area well developed ( Fig. 5). Haltere with brown knob and yellow–brown pedicel, with a row of setae beginning from the base of the pedicel, quite abundant at the knob.

Legs. Legs elongate, brown, setae arranged in regular rows along tibiae and tarsi. All tibiae with a single apical spur, front spur very short, mid spur three times tibia width, hind spur more four times tibia width. Apex of hind tibia with a regular row of longer setae along distal margin. Tibiae and tarsi with setae arranged in regular rows. Tarsal claw with three basal teeth ( Fig. 6)

Wing. Wing membrane smoky brown, veins darker ( Fig. 7). C extending to just beyond R5. Sc complete, reaching C beyond origin of Rs. Rs originating basally; R4 absent; R5 reaching C before wing apex; R1 long, reaching C beyond medial fork. Medial fork long, more than twice the free length of M1+2, M2 ending slightly before wing margin; no bM fold; A1 sclerotized, incomplete. Microtrichia densely covering wing membrane; macrotrichia present on R1, R5, and at base of CuA, absent on medial veins and on A1.

Abdomen. Tergites brown, sternites lighter. Terminalia brown. Segments 2 and 3 about twice length of segment 1 ( Fig. 8 ).

Terminalia. Male terminalia elongated anteriorly ( Fig. 9 ). Gonocoxites mesally fused at the anterior margin, with scattered setae laterally and densely pilose internally, gonostyles inserted apically; no mesal projection of syngonocoxite (“ intercoxalia ”). Gonostyle enlarged apically, densely covered with setae distally, no spines present ( Fig. 10 ). Aedeagus elongated, anterior corners short, projected basally. Tergite 9 triangular, wide at base, slender toward apex.

Female. As male in most features. Terminalia with S8 as a pair of largely developed gonapophyses, reaching more distally than the cerci and almost as wide as segment 7, involving the reduced, remaining of the terminalia. T8 nearly absent, visible only as a small plate around a single mesal setae anteriorly to T9. T9 present as a pair of more or less separated lobes with some few setae. T10 apparently absent, cerci unisegmented, postgenital plate (S10) elongated beyond distal end of cerci, ventrally to the anal membrane, with setae ( Fig. 11–13 ).

Larva. In general terms similar to other Keroplatinae larvae. General color dark yellowish, head capsule brown ( Fig. 12 ). No distinctive modification of the body cuticle, except for ventral pairs of transverse lines of modified texture of the integument ( Fig. 13 ). Cephalic capsule with well developed gena, frontal area unsclerotized posteriorly, not as large as in other genera ( Fig. 14 ). Eye ventral to the antenna. Coronal area considerably developed, sagittal crest of frons evident, ventral part of foramen magnum longer than wide. Antenna placed more dorsally, considerably wide, flattened as in other members of the family, with an anterior pointed projection. Mandible well developed, with five stronger apical teeth; three sensorial depressions present as typically in other members of the family. Maxilla elongated, rather parallel distally, with eight teeth at the inner border, palpifer weakly sclerotized, wider distally than basally. Cardo slender, transverse, with two pairs of setae laterally ( Fig. 15 ). Prelabial sclerite V–shaped, as in other genera. Thoracic segments short, abdominal segments long, except first and last ( Fig. 16 ). Secondary annulation on abdominal segments. Posterior end with a pair of lobose triangular projections ( Fig. 17 ).

Biology. The larvae of the Chinese Keroplatini species described here were first found in the Shennong Gong caves by Xuezhen Li and Changying Niu (Huazhong Agricultural University, China) in late December 2005. This discovery in Shennong Gong followed earlier reports by Arthur Clarke (University of Tasmania, Australia) from October 2000, with observations and collections of non-glowing keroplatid larvae from caves in several other provinces of China, including northwest Guangxi, northwest Zhejiang and eastern Yunnan, ( Clarke 2000, 2001a, b, 2002a, b, 2004a, b, 2006a), plus the more recent observations and collections in caves of the elevated plateau karst region of Lichuan County, in western Hubei Province. They were later collected in Shennong Gong in early November 2006, when an abundant population of the larvae was located in a streamway chamber, quite close to an entrance (the tourist cave exit).

Shennong Gong is a stream cave, with a surveyed length of approximately five kilometers from the insurgence (stream entry) point near Pan Ling village to its known downstream resurgence; the first 450–500m of the cave has been recently developed as a tourist show cave. Beyond the main zigzag passage (tourist section), the underground stream extends several kilometers into the cave, creating a relatively constant year round temperature (18±2OC) and high humidity (98±2% rH) environment. The Keroplatini larvae are mainly distributed within a distance of up to 150–200 m from the entrance of the cave, where there is good ventilation and moist air flow following the course of inflowing stream water. The larvae are suspended from the moist roof of the cave above or adjacent to the streamway. Their numerous, long sticky silken ensnare threads coated with mucous droplets to enhance the capture of prey, chiefly flying insects, including the adult forms of the larvae.

The species does not show any troglobiontic modifications. The colonies of larvae are found in the cave throughout the year. Similarly to what is seen in other Keroplatidae species, e.g., the Tasmanian glow–worms ( Ferguson 1925, Clarke 2001c, 2006b), the larval stage may last 5–12 months, depending on the environmental conditions and prey availability. Large numbers of pupae are observed at the cave roof at the end of June, where they remain suspended horizontally from the silk threads. The pupal stage lasts 7–10 days in this cave. July is the peak time of adult emergence. Mating usually takes place immediately upon female emergence, if adult males are available. The adult life span is short. Females live 3–5 days and males 5–7 days. The eggs are black in color and round in shape. Egg development time is 12–30 days. The biology of the species will be explored in more detail elsewhere.

Etymology. The name of the species comes from the name of the cave, Shennong Gong, which means “Dragon Palace”.

Figures

FIGURES 1 – 4. Chetoneura shennonggongensis, sp. n. 1. Head, with reduced mouthparts and palpus. 2. Base of antenna, with scape, pedicel, and elongated first flagellomere. 3. Laterally compressed flagellomeres. 4. Lateral view of thorax, with weakly sclerotized mediotergite with setae ventrally. Abbreviations: anep, anepisternum; epm III, metepimeron; eps III, metepisternum; flag, flagellomere; ktep, katepisternum; lab, labella; lat, laterotergite; mxp, maxillary palpus; ped, pedicel; sca, scape; sctl, scutellum. (Photos by D. S. Amorim).

FIGURES 8 – 13. Chetoneura shennonggongensis, sp. n. 8. Base of abdomen, with elongated segment 2. 9. Male terminalia, ventral view. 10. Gonostyle, ventral view. 11. Female terminalia, ventral view. 12. Female terminalia dorsal view. 13. Female terminalia, dorsal view. Abbreviations: abd seg, abdominal segment; ae, aedeagus; ce gc, gonocoxite; ga VIII, gonapophysis of sternite 8; gs, gonostyle; S 8, segment 8; S 9, sternite 9; S 10, sternite 10; T 8, tergite 8, T 9, tergite 9. (Photos by D. S. Amorim).

FIGURES 14 – 17. Chetoneura shennonggongensis, sp. n., 14. Larva habitus. 15. Posterior end of larva. 16. Head capsule of larva, dorsal view. 17. Head capsule of larva, ventral view. Abbreviations: ant, antenna; car, cardo; clyp scl, clypeal sclerite; cor ar, coronal area; for mag, foramen magnum; fr cr, frontal crest; fr scl, frontal sclerite; gen, gena; lbr scl, labral sclerite; mand, mandible; max, maxilla; pr scl, prelabial sclerite. (Photos by D. S. Amorim).