Deuterophlebia pachychaeta, Zheng & Zhou, 2023

Zheng, Xuhongyi & Zhou, Changfa, 2023, Two new species of Deuterophlebia Edwards, 1922 from Southwestern China (Diptera, Deuterophlebiidae), Deutsche Entomologische Zeitschrift 70 (2), pp. 387-401 : 387

Deuterophlebia pachychaeta sp. nov.

Description.

Male adults. Body length ca. 3.0 mm (n = 2), uniformly brownish black. Head brownish black, flattened and nearly trapezoidal, width ca. 0.50 mm (Fig. 6A ). Head densely covered with microtrichia. Median clypeal lobe slightly convex, semicircle shaped with around 20 sharp setae (Fig. 6A ). Mouthparts in form of an invaginated tubule, oral region depressed (Fig. 6A, B ). Edges of oral region (or mouth opening) ridged, forming a protruded angle on inner side of each eye (Fig. 6A, B ). Ventral ridge of oral region convex medially and forming a blunt mental tooth (Fig. 6A, B ). Postgena and oral region with microtrichia but more sparse than other regions, a pair of tentorial pits present on each side of oral region (Fig. 6A, B ). Compound eyes glabrous, width ca. 0.13 mm, distance between eyes ca. 0.30 mm (Fig. 6A ).

Antennae ca. 13.0 mm (n=5) (Fig. 6A, C ). Scape oval shaped, pedicel globular, both scape and pedicel covered with microtrichia (Fig. 6A, C ). Flagella four segmented, flagellomeres I-III slender cylindrical, each with a subapical tubercle on front margin and bearing 8-10 digitiform setae (Fig. 6C ). Flagellomere IV flattened and elongated, with curved hair-like setae on the anterior side of basal half, apical half generally glabrous but bearing 4-5 clusters of curved hair-like setae, apex slightly expanded with some curved hair-like setae (Fig. 6C ). Antennal ratio ca. 4.0: 2.0: 5.0: 3.0: 3.0: 287.0, flagellomere IV about 17 × combined length of five basal antennal articles or about 4 × body length (Fig. 6C ).

Thorax brownish black, densely covered with microtrichia. Mesonotum strongly expanded. Wings ca. 5.5 mm, shape, venation and other features similar to D. pseudopoda sp. nov. (Fig. 1 ).

Legs brownish black, slender, three pairs sharing similar chaetotaxy exhibiting four types of setae: (1) microtrichia, densely covered on all segments; (2) sharp macrotrichia, sparsely on dorsal margin of femora and tibiae; (3) long capitate setae, on ventral side of tarsomere I-IV of each leg, distal half of ventral edge of all tibiae, surrounding the top of fore- and midtibiae, and also densely arranged radially on each empodium; (4) digitiform setae, 1-3 pairs for each tarsomere (Fig. 6D-F ). In foreleg, femur: tibia: tarsus = 11.0: 17.0: 16.0; femur slightly flattened, tibia slender cylindrical and gradually broader apically; tarsomere I: II: III: IV: V = 8.5: 2.0: 2.0: 1.5: 0.8, tarsomeres I-IV cylindrical, tarsomere V conical; empodium shell-shaped, length subequal to tarsomere V; claw slender tapered, shorter than empodium (Fig. 2B ) (Fig. 6D ). Midleg shortest among all legs, features generally similar to foreleg, femur: tibia: tarsus = 10.0: 12.5: 14.0, tarsomere I: II: III: IV: V = 8.5: 2.0: 2.0: 1.5: 0.8 (Fig. 6E ). In hindleg, femur: tibia: tarsus of hindleg = 14.0: 17.0: 11.0, tarsomere I: II: III: IV: V = 3.0: 2.0: 2.0: 1.5: 0.8 (Fig. 6F ).

Abdomen brownish black, densely covered with microtrichia, nine segmented, tapering posteriorly. Segment VIII in form of a short chitin ring, sternite IX almost glabrous, connected with dorsal plate and gonocoxite (Fig. 6G ). Gonocoxite with posterior projection ca. 1/2 length of gonostylus (Fig. 6G ). Gonostylus subequal dorsal plate, flattened, slender oval shaped, flexor surface with numerous curved sharp setae (Fig. 6G ). Dorsal plate parallel-sided, posterior margin slightly depressed with a median cleft and some stout setae on margin (Fig. 6G ). Aedeagus in form of a smooth tube, length subequal to gonostylus, longer than dorsal plate (Fig. 6G ).

Female adult. Body length ca. 2.3 mm (n = 1). Besides sexual differences, generally similar to the males except following features (Fig. 7A-D ).

Head width ca. 0.40 mm (Fig. 7A ). Median clypeal lobe slightly convex with ca. 20 setae (Fig. 7A ). Oral region located near anterior margin of head, postgena and oral region with microtrichia but more sparse than other regions (Fig. 7A ). Compound eyes more prominent than males (Fig. 7A ). Antenna ca. 0.3 mm. Scape slender oval-shaped, pedicel globular, both scape and pedicel covered with microtrichia with several sharp setae (Fig. 7A ). Flagellomere I slender cylindrical, flagellomeres II-III slender oval shaped, flagellomere IV dripping shaped (Fig. 7A ). Flagellomeres I-IV bearing 2, 4, 10 and 2 digitiform setae apically respectively, flagellomere III-IV with 1 and 4 sharp setae respectively (Fig. 7A ). Antennal ratio = 7.0: 4.0: 10.0: 5.0: 5.0: 4.0 (Fig. 7A ).

Legs sharing similar chaetotaxy and exhibiting three types of setae, chaetotaxy similar to males but without capitate setae (Fig. 7B-D ). In all legs, coxae about twice longer and broader than trochanters, femora slightly flattened, tibiae and tarsomeres slender cylindrical (Fig. 7B-D ). In foreleg and midleg, femur: tibia: tarsus = 1.0: 2.0: 1.5, tarsomere I: II: III: IV: V = 1.2: 0.8: 0.8: 0.8: 2.4 (Fig. 7B, C ). In hindleg, femur: tibia: tarsus = 1.0: 1.7: 1.1, tarsomere I: II: III: IV: V = 1.0: 0.8: 0.8: 0.8: 2.4 (Fig. 7D ). Claws of all legs similar, paired, stout and curved, with a blunt protrusion in the middle (Fig. 7B-D ). Empodium in form of a long and hairy spine, subequal to the length of claw (Fig. 7B-D ).

Male pupae. Pupae flattened oval shaped, length 2.8 mm (n = 2), width 2.0 mm (Fig. 8A, B ). Dorsal integument dark brown, divided into 11 segments (Fig. 8A, B ).

Prothorax fused with mesothorax, forming a conical segment with a median suture (Fig. 8A, B ). Mesothoracic lateral margins each with a pair of sharp spines and a gill (Figs 8A, B , 9A, B ). Spines ca. 0.4 mm, expanded basally, slightly curved, dark brown, originated from a round base (Fig. 9A ). Ventral gills light to dark brown, length subequal to the dorsal spines, each including four filaments: posterior filament single and short, pointing backward; anterior three gill filaments on a common base, similar in shape, slender and twisted; second and third filaments fused at base (Fig. 9B ). Metathorax completely surrounded by mesothorax and first abdominal segment (Fig. 8A, B ).

Abdominal segment I and II similar, each with a pair of anterolateral projections, each projection pointing forward and bearing ca. 18 spines (Fig. 8A, B ). Lateral margins of segments VI and VII with several spines on both dorsal and ventral sides. Segment VIII shield-shaped, surrounded by segments VII and IX (Fig. 8A, B ).

Adult structures visible on ventral side (Fig. 8B ). Head present below mesothorax; antennal sheaths in form of a large elliptic ring, surrounding body 2.0 times (Fig. 8B ). Leg sacs extended to posterior end of antennal ring, strongly expanded apically. Abdominal segments III-V each with a pair of black adhesive discs (Fig. 8B ).

Female pupae. Length ca. 2.8 mm (n = 1), width ca. 2.0 mm (Fig. 8C, D ). Dorsal morphology similar to male except for smaller mesothorax (Fig. 8C, D ). Gender can be identified through the absence of antennal ring, apex of female leg sheaths not expanded (Fig. 8C, D ).

Material examined.

Holotype: male adult, China: Yunnan Province, Nujiang Lisu Autonomous Prefecture, Gongshan County, Dulongjiang Township , Dulongjiang River , 27°50'14.16"N, 98°19'54.2"E, 1470 m a.s.l., 4.II.2023, Xuhongyi Zheng leg. Paratypes: 1 male adult, 2 male pupae, same locality and data as holotype ; 1 female adult dissected from a pupa, Yunnan Province, Nujiang Lisu Autonomous Prefecture , Fugong County, 26°57'17.32"N, 98°52'3.04"E, 1265 m a.s.l., 3. VII. 2022, leg. Xuhongyi Zheng, Zhenxing Ma, Zhiteng Chen & Pengxu Mu.

Diagnosis.

Male adults of Deuterophlebia pachychaeta sp. nov. can be identified by their head shape and chaetotaxy of antennae (Fig. 6A, C ). Following the keys of Courtney (1994) and Zheng et al. (2022), males of this species, which are similar to D. mirabilis Edwards, 1922, D. blepharis Courtney, 1994 and D. sinensis Zheng et al., 2022, can be separated from other Asian species by their relatively long antennae (longer than 8.0 mm), and postgena covered with microtrichia (Fig. 6B ). Chaetotaxy on flagellomeres can be used to differentiate those four similar species: in the new species, there were ca. 8-10 digitiform setae on each of flagellomeres I-III (Fig. 6A, C ) ( Courtney 1990, 1994; Zheng et al. 2022).

Female adults of D. pachychaeta sp. nov. can be recognized through a combination of the smooth median clypeal lobe, chaetotaxy of antennae, and shape of flagella (Fig. 7A ). Its smooth and convex median clypeal lobe is similar to D. mirabilis Edwards, 1922, D. blepharis Courtney, 1994, D. sinensis Zheng et al., 2022, D. yunnanensis Zheng et al., 2022 and D. wuyiensis Zheng et al., 2022, but can be differentiated from them by its antenna: flagellomeres I-IV bearing ca. 2, 4, 10 and 2 digitiform setae respectively, flagellomere IV with additionally 4 sharp setae; antennal ratio = 7.0: 4.0: 10.0: 5.0: 5.0: 4.0 (Fig. 7A ) ( Courtney 1990, 1994; Zheng et al. 2022).

Pupae can be identified by their mesothoracic spines: there are two spines on each side, expanded basally (Fig. 9A, B ). Compared with the 15 species with a clear pupal stage ( Courtney 1990, 1994; Zheng et al. 2022), only D. acutirhina Zheng et al., 2022 has similar basally expanded spines, but less expanded than in the new species. They can also be distinguished by the absence of abdominal dots ( Zheng et al. 2022).

Etymology.

The specific epithet " pachychaeta " is a combination of the words pachy and chaeta, which refers to its thickened spines on pupal mesothorax.

Distribution.

China (Yunnan Province).

Figures

Figure 1. Male adult of D. pseudopoda sp. nov. Scale bar: 1.0 mm.

Figure 2. Male adult of D. pseudopoda sp. nov.: A. Head (ventral view); B. Oral region (ventral view); C. Flagellomeres; D. Foreleg; E. Midleg; F. hindleg; G. Terminalia (dorsal view). Abbreviations: cp, median clypeal lobe; pd, pedicel; fl, flagellomere; or, oral region; mt, mental tooth; pg, postgena; co, coxa; tr, trochanter; fe, femur; tb, tibia; ts, tarsomere; em, empodium; dp, dorsal plate; gc, gonocoxite; gs, gonostylus; ad, aedeagus. Scale bars: 0.1 mm (A, C, G); 0.05 mm (B); 0.5 mm (D-F).

Figure 6. Male adult of D. pachychaeta sp. nov.: A. Head (ventral view); B. Oral region (ventral view); C. Flagellomeres; D. Foreleg; E. Midleg; F. Hindleg; G. Terminalia (dorsal view). Scale bars: 0.1 mm (A, C, G); 0.05 mm (B); 0.5 mm (D-F).

Figure 7. Female adult of D. pachychaeta sp. nov.: A. Head (ventral view); B. Foreleg; C. Midleg; D. Hindleg. Scale bars: 0.1 mm.

Figure 8. Pupae of D. pachychaeta sp. nov.: A. Male pupa (dorsal view); B. Male pupa (ventral view); C. Female pupa (dorsal view); D. Female pupa (ventral view). Scale bars: 1.0 mm.

Figure 9. Male pupa of D. pachychaeta sp. nov.: A. Thoracic spine (dorsal view); B. Gill (ventral view). Scale bar: 0.1 mm.