Psectrocladius (Psectrocladius) malum Liu, 2025

Liu, Wenbin, Tang, Yaning, Nie, Jiaxin, Shao, Ziming, Cao, Wei & Yan, Chuncai, 2025, Three new species of Psectrocladius Kieffer (Diptera, Chironomidae) from China, ZooKeys 1239, pp. 33-50 : 33-50

Psectrocladius (Psectrocladius) malum Liu sp. nov.

Figs 7 , 8 , 9

Material examined.

Holotype: • male ( TJNU No. 12521), China, Inner Mongolia Autonomous Region, Xilinhot City , 43°57'29"N, 116°03'41"E, 1020 m, 10.VIII.1997, H. H. Li, sweep.

Diagnosis.

The base of gonocoxite with a small convex, the mid-upper part of gonocoxite with obvious concave, the outlines of both the left and right sides create a shape reminiscent of an apple. The end of inferior volsella pendulous and tongue-shaped.

Description.

Male (N = 1).

Total length 4.07 mm. Wing length 2.04 mm. Total length / wing length 2.00. Wing length / length of profemur 2.32. Thorax yellow to brown, with dark brown patterns. Abdomen II – V yellow, abdomen VI – VIII yellowish brown.

Head (Fig. 7 B ). AR 1.70. Temporal setae 13; including 4 inner verticals; 3 outer verticals; and 6 postorbitals. Clypeus with 16 setae. Tentorium 116 μm long. Palpomere lengths (II – V in μm): 54, 102, 89, 203. The ratio of the length of V to III: 2.00.

Thorax (Figs 7 C , 9 B ). Antepronotum with 7 setae, acrostichals absent, dorsocentrals 6, prealars 6. Scutellum two setae.

Wing (Figs 7 A , 9 A ). Anal lobe developed. VR 1.17. Costa extension 43 µm. The end of R 2 + 3 is between R 1 and R 4 + 5. Radius with 9 setae. R 1 with one seta. Squama with two setae. Brachiolum with two setae.

Legs (Fig. 7 E – G ). Front legs, mid legs and hind legs each with one tibial spur, length is 70, 55, 65 µm. The tibial comb of hind legs with 17 spurs. Tarsus I of fore legs with one pseudospurs. Tarsus I, II and III of mid legs with two pseudospurs. Tarsus I, II and III of hind legs with two pseudospurs. Lengths (in μm) and proportions of legs as in Table 3 .

Hypopygium (Figs 8 A, C, D , 9 C, D ). Tergite IX with 15 setae located two sides and the base of anal point. Tergite paratergital 11 setae. Anal point 14 µm long. The base of anal point 8 µm wide. Transverse sternapodeme 128 µm long, central slightly arched, with well-developed bilateral ossified processes, triangle-shaped. Virga 53 µm long. The end of inferior volsella pendulous and tongue-shaped. Outer margin of inferior volsella semicircular. Gonocoxite 303 µm, the base of gonostylus with a small convex, base outer margin of gonocoxite concave, the left and right contours form apple shaped. Gonostylus 166 µm, Megaseta 18 µm. HR 1.83; HV 2.45.

Distribution.

China (Inner Mongolia).

Etymology.

From the Latin, malum , apple, referring to the convex and concave upper inner margin of the two sides of the gonocoxite, which has an apple-like form.

Remarks.

The gonocoxite morphology provides crucial diagnostic characters for distinguishing Psectrocladius species. Psectrocladius (Psectrocladius) malum Liu , sp. nov. is characterized by a unique concave inner margin at the base of its gonocoxite, representing a distinctive apomorphic feature. This condition contrasts markedly with P. (P.) semicirculatus Sæther, 1969 , which exhibits a more complex gonocoxite structure featuring both concave and convex inner margins. Furthermore, P. (P.) malum Liu , sp. nov. can be unequivocally differentiated from P. (P.) semicirculatus by its distinctive tergite XI morphology and anal point configuration.

Comparative analysis reveals that the anal point morphology of P. (P.) malum Liu , sp. nov. shows notable similarities with that of P. (P.) sokolovae Zelentzov & Makarchenko, 1988 . However, these species can be readily distinguished by several quantitative characters: P. (P.) sokolovae possesses (1) a significantly higher antennal ratio (AR) and (2) a greater overall body length. Additionally, while P. (P.) barbimanus ( Edwards, 1929) also displays a slight concavity on the outer margin of the gonocoxite base, this species is immediately recognizable by its distinctive pear-shaped overall morphology, providing a clear diagnostic feature for species identification.

Figures

Figure 7. Psectrocladius (Psectrocladius) malum Liu, sp. nov., holotype male A wing B head C thorax D foreleg E midleg F hindleg G tarsus V. Scale bars: 100 μm (A, B, C, D, E, F); 20 μm (G).

Figure 8. Psectrocladius (Psectrocladius) malum Liu, sp. nov., holotype male A hypopygium B abdomen C anal point D volsella. Scale bars: 100 μm (A, B); 20 μm (C, D).

Figure 9. Psectrocladius (Psectrocladius) malum Liu, sp. nov., holotype male A wing B thorax C hypopygium, dorsal view D hypopygium, ventral view.