Paratanytarsus zengensis, Li & Tang, 2021

Li, Zhiqiang & Tang, Hongqu, 2021, Two new species of Paratanytarsus Thienemann & Bause (Diptera: Chironomidae) from Oriental China, Zootaxa 4903 (3), pp. 430-438 : 434-437

Paratanytarsus zengensis sp. n.

( Figs. 3–4 )

http://zoobank.org/ urn:lsid:zoobank.org:act:4CE805DC-D3BD-4217-8FBE-A97A6BDD1995

Type material. Holotype, adult male, CHINA: Guangdong Province, Guangzhou City, Zengcheng District, Zhengguo Town , Shuimei Country , Lan Stream , 23°21′N, 113°58′E, alt., 160 m, 13.xii.2018, H.Q. Tang . Paratypes: 1 male, 1 pupal exuviae, as holotype; 1 adult male, as previous, except 4.i.2020, Z.Q. Li; 1 pupal exuviae, Hongkong SAR, Tai Po, Ng Tung Chai waterfall, 22°26′N, 114°08′E, alt. 15 m, 30.iv.2016, K.-C. Li.

Derivatio nominis. From the type locality, Zeng City, also called ‘ Zengcheng ’ in Chinese Pinyin, ‘ zeng ’ means plus or additional, referring to the additional lobe of superior volsella.

Diagnosis. Adult male. Scutum with large tubercle, digitus of superior volsella bearing inner tubercle with apical seta, median volsella short, with several setiform and spoon-shaped lamellae. Pupa. T III with paired, posterior wedge-shaped spine patches, T IV–V each with single, oval anteromedian spinule patch. Posterolateral comb on A VIII with 3–4 small teeth.

Description. Male (n = 2). Total length 2.5–2.6 mm. Wing length 1.4–1.5 mm.

Coloration. Body yellow; thorax light brown on scutal vittae and postnotum; T VI–VIII light brown. Wing with yellow undertone. All legs pale yellow except slightly darkened tibiae and sub-apices of femora; foretarsi brownish.

Head. Temporals 8–10. Antenna with 13 flagellomeres; terminal flagellomere 324–375 μm long; AR 0.65–0.82. Frontal tubercles conical, 7–10 μm long. Lengths of palpomeres 2–5 (μm): 35–38, 90–95,100–105, 180–190. Clypeus with 20–24 setae.

Thorax. Ac 18–22, biserial; Dc 10–12; H absent; Pa 1; Scts 4–5. Scutal tubercle large.

Wing. VR 1.16–1.20.

Legs. Foretibia with straight spur 10–12 μm long. Mid and hind tibiae with combs separated; comb spur 20–25 μm long in mid tibia and 25–30 μm long in hind tibia. Ratios of leg segments: LR 1 1.93–2.00, BV 1 1.70–1.75, SV 1 1.33–1.41; LR 2 0.60–0.65, BV 2 3.63–3.73, SV 2 3.65–4.03; LR 3 0.69–0.73, BV 3 2.61–2.64, SV 3 3.07–3.21.

Hypopygium ( Fig. 3A ). Anal tergite bands separated, each distal end with 3–4 strong setae on basal tubercles; anal point rounded or evenly tapered distally; paired crests well developed ( Fig. 3B ). Gonocoxite 90–100 μm long. Superior volsella ( Fig. 3D ) rounded, with 4–5 dorsal and 4 inner marginal setae, without microtrichia; digitus robust, pointed apically, with inner tubercle bearing seta. Median volsella short, 15–20 μm long, not extending beyond superior volsella, with several setiform and spoon-shaped lamellae ( Fig. 3C ). Inferior volsella apically swollen and rounded, with several recurved setae. Gonostylus 100–108 μm long, 4.0–4.6 times as long as broad at middle; HR 0.86–1.00.

Pupa (n = 2). Total length 3.1–3.5 mm.

Coloration. Mostly pale brown; T IV–V each with dark, oval anteromedial spinule patches.

Cephalothorax ( Fig. 4A ). Frontal setae 100–150 μm long, ca twice as long as distance between them. Thoracic horn 300–360 μm long, with short setae. Antepronotals 2; precorneals 3, including 1 strong and 2 weak setae. Dosocentrals 4, all simple, 50–75 μm long. Prealar tubercle present. Wing sheath with low nose; pearl row present.

Abdomen ( Fig. 4B ). T I and VIII without spinulation. T II with extensive spinulation; paired, rectangular point patches present posteriorly. Hook row 230–265 µm long, 0.62–0.65 times as long as segment width, with 120–150 hooklets. Pedes spurii A absent, pedes spurii B distinct on A II.T III anteriorly bare, posteriorly with paired, curved or wedge-shaped patches of 55–70 slender spines, 75–95 μm long. T IV–V each with single, oval anteromedian spinule patch bearing anterior neck; paired, elongated point patches posterior to anteromedian patch on TV. T VI with one anteromedian and paired, longitudinally elongated median point patches. T VII with paired point patches only. T IX with paired, weak anterolateral point patches. Posterolateral comb ( Fig. 4C ) of A VIII with 3–4 small teeth. Number of Lt-setae on A IV–VIII: 2, 3, 4, 4, 5, respectively. Anal lobe 130–150 μm long, anal lobe ratio 1.24–1.50, with one dorsal seta and fringe of 24–26 taeniae; male genital sac 90 μm long, extending beyond anal lobe.

Female and larva. Unknown.

Discussion. The male of Paratanytarsus zengensis sp. n. will not key past couplet 2 in Cranston et al. (1989), because of the combination of the robust digitus, the apically rounded anal point and the large scutal tubercle. The male is somewhat similar to that of P. koreanus Reiss & Säwedal of the kaszabi group in the anal point with a rounded apex, the sharply pointed digitus with a setiferous inner tubercle, and the short median volsella, barely reaching the apex of superior volsella, with spoon-shaped setae, but the distinctively structured digitus resembles the so-called “ Micropsectra -seta” which is known from several close genera of the Micropsectra series ( Säwedal 1982, Giłka & Jażdżewska 2010). A location/arrangement of the seta, digitus, and superior volsella in Paratanytarsus zengensis , with the seta and its tubercle distinctly moved from base of the volsella towards the digitus apex differs, however, from those in other members of this heteromorhic genus (cf. Giłka 2009, Giłka & Dobosz 2015), being thus defined as the unique feature.

Because of the T IV without lateral longitudinal spine or spinule patches and the T V with paired, weak lateral longitudinal point patches, the pupa will not key past to couplet 6 in Pinder & Reiss (1986). The pupa somewhat resembles that of P. tenuis (Meigen) in the abdominal spinulation, but differs in the well-developed, largely setiferous thoracic horn, the T III with wedge-shaped, large posterior spine patches, and T VI–VII with paired longitudinal point patches. According to Reiss & Säwedal (1981, fig.31) and Langton & Visser (2003, figs. 132e, f), the latter has small and largely bare thoracic horns, oval and relatively small posterior spine patches on T III, and no longitudinal point patch on the T VI–VII.

Biology and ecology. In the cold seasons, the specimens were collected from two mountain streams with depth no more than 40 cm, water temperature 13.1–18.9℃, and dissolved oxygen 6.5–7.9 mg /l.

Figures

FIGURE 3. Paratanytarsus zengensis sp. n., male. A, Hypopygium, dorsal view; B, anal tergite with anal point; C, median volsella; D, superior volsella, ventral view. Scale: A–D, 25 µm

FIGURE 4. Paratanytarsus zengensis sp. n., pupa. A, Cephalothorax, lateral view; B, abdomen, dorsal view; C, anal comb of abdominal segment VIII, dorsal view. Scale: A–B, 100 µm; C, 25 µm.