Psectrocladius (Psectrocladius) gracilis Liu, 2025

Psectrocladius (Psectrocladius) gracilis Liu sp. nov.

Figs 4 View Figure 4 , 5 View Figure 5 , 6 View Figure 6

Material examined.

Holotype: • male ( TJNU No. 1210), China, Inner Mongolia Autonomous Region, Ulansuhai Nur , 40°55'19"N, 108°50'66"E, IV.1982, X. H. Wang. Sweep . Paratypes: • two males, same data as holotype .

Diagnosis.

Thorax and abdomen dark. Anal tergite inverted triangle, both sides with a reticulate pattern; anal point mid-length, uniform thickness, gonostylus narrow and long.

Description.

Male (N = 3, unless stated).

Total length 3.63–3.66, 3.65 mm. Wing length 2.00, 2.15 (2) mm. Total length / wing length 1.69, 1.82 (2). Wing length / length of profemur 2.43, 2.36 (2). Thorax dark brown to black, abdomen yellowish brown (Fig. 5 B View Figure 5 ).

Head (Fig. 4 B View Figure 4 ). AR 1.67–1.97, 1.80. Temporal setae 10–12, 11; including 2–4, 3 inner verticals; 3–6, 4 outer verticals; and 2–5, 4 postorbitals. Clypeus with 9–11, 10 setae. Tentorium 150–164, 155 μm long. Palpomere lengths (II – V in μm): 48–62, 56; 86–107, 97; 110–130, 113; 131–160, 148. The ratio of the length of V to III: 1.35–1.86, 1.55.

Thorax (Figs 4 C View Figure 4 , 6 B View Figure 6 ). Antepronotals 4–10, 7, acrostichals absent, dorsocentrals 10–16, 13, prealars 4–8, 6. Scutellum with 4–6, 5 setae.

Wing (Fig. 4 A View Figure 4 , 6 A View Figure 6 ). Anal lobe developed. VR 1.16, 1.23 (2). Costa extension 55, 58 (2) µm. The end of R 2 + 3 is between R 1 and R 4 + 5. Radius with 5 (1) setae. Squama with 29 (1) setae. Brachiolum with one seta.

Legs (Fig. 4 E – G View Figure 4 ). Front tarsomeres without bristles, tibial comb with one spur, 68–83, 74 µm long, mid tibia with two spurs, one is 53–55, 53 µm long, one is thin and small, 8–10, 9 µm long. Hind tibia with one spur, 70–75, 73 µm long. The tibial comb of mid legs with 13–17, 14 spurs. Tarsus I of mid legs with two pseudospurs. Tarsus II of mid legs with 1–2 pseudospurs. Tarsus III of mid legs with two pseudospurs. Tarsus I and II of hind legs with two pseudospurs. Lengths (in μm) and proportions of legs as in Table 2 View Table 2 .

Hypopygium (Figs 5 A, C, D View Figure 5 , 6 C, D View Figure 6 ). Tergite IX with 13–19, 15 setae ascending along both sides of the base of anal point. Tergite paratergital 10–15, 12 setae. Anal tergite inverted triangle, both sides with a reticulate pattern. Anal point mid-length, 20–29, 25 µm long, uniform thickness. Transverse sternapodeme 115–138, 124 µm long, central slightly arched, with well-developed bilateral ossified processes. Virga 75–80, 78 µm, the top of virga a small part is hook-shaped. Dorsal volsella square-shaped, ventral circular. Both sides of volsella with setae. Gonocoxite 250–276, 266 µm. Gonostylus 117–130, 123 µm, megaseta 12–17, 15 µm. HR 2.08–2.26, 2.16; HV 2.79–3.11, 2.97.

Distribution.

China (Inner Mongolia).

Etymology.

From the Latin, gracilis , narrow and thin, referring to the character of tergite IX and gonostylus, adjective in the nominative singular.

Remark.

The newly described species, Psectrocladius (Psectrocladius) gracilis Liu , sp. nov., exhibits significant morphological affinities with P. (P.) jintuoctadecimus ( Sasa, 1996) in several diagnostic characters. These shared characteristics include: (1) the structural configuration of the inferior volsella, (2) the distinctive reticulate patterning on the lateral aspects of tergite XI, and (3) comparable measurements of both antennal ratio (AR) and leg ratio (LR). However, P. (P.) gracilis Liu , sp. nov. can be readily distinguished by its elongate and slender anal point and gonostylus, which contrast markedly with the nearly triangular morphology observed in P. (P.) jintuoctadecimus ( Sasa, 1996) , particularly in the latter’s characteristic broad-tipped gonostylus that significantly exceeds its basal width.

Furthermore, while P. (P.) gracilis Liu , sp. nov. shares certain anal point characteristics with P. (P.) limbatellus (Holmgren, 1869) , the two species are clearly differentiated by their gonostylus morphology. The gonostylus of P. (P.) gracilis Liu , sp. nov. is diagnostically characterized by its notably narrow and attenuated structure, representing a distinct morphological divergence from the gonostylus configuration observed in P. (P.) limbatellus .