Psilotreta longicornis, Yang & Hu & Morse, 2020

Yang, Lian-Fang, Hu, Ben-Jin & Morse, John C., 2020, Interesting new Chinese species of Leptoceridae and Odontoceridae (Insecta: Trichoptera) from several recent collecting efforts, Zootaxa 4732 (1), pp. 138-160 : 157-159

Psilotreta longicornis sp. n. Yang & Morse

( Fig. 11 )

Oláh & Johanson (2010) established three species groups for this genus, they summarized diagnostic characters for the Psilotreta trimeresuri Species Group as follows: (1) harpagones originate mesally on coxopodites; (2) numerous small spines are present on the apex of the harpagones, and (3) there are 2 pairs of spines in the phallic apparatus. Our new species seems to have the typical diagnostic characters (1) and (2), however, there is only one pair of paramere spines in our new species, which is the main character for their Psilotreta japonica Species Group. Based on our study of Chinese species, character (1) (“harpagones originate mesally on coxopodites”) is actually caused by the well-developed ventral lobe along the ventral margin of the coxopodite ( Fig. 11A ), the shape and size of this ventral lobe varying in different species. So far, a total of 12 species have been found in southern China which possess some character combination of the above two species groups: Coxopodites having well-developed ventral lobes, dense small spines present on the apex of the harpagones, and the phallus having only one pair of paramere spines. Those species are the following: Psilotreta kwantungensis Ulmer 1926 , Ps. lobopennis Hwang 1957 , Ps. anfracta Yuan & Yang 2008 , Ps. expers Yuan & Yang 2008 , Ps. rectangular Yuan & Yang 2008 , Ps. spinata Yuan & Yang 2008 , Ps. tenuispina Yuan & Yang 2008 , Ps. applanata Yuan & Yang 2010 , Ps. dardanos Malicky 2000 , Ps. grossa Yuan & Yang 2010 , Psilotreta horrida Yuan & Yang 2010 , Psilotreta yunnanensis Yuan & Yang 2010 .

Diagnosis. This new species is most similar to Psilotreta anfracta from southeastern China (Jiangxi), but differs from it by the following characters: (1) The dorsal process of abdominal segment X is broadly hood-like, with long horn-like lateral processes produced basoventrally (the dorsal process of X is slender and cylindrical, with lateral processes produced apicoventrally in Ps. anfracta ); (2) the ventral processes of segment X are broadly crescentic, each with its sharp end directed anterad (they are sickle-shaped, each with a long “handle” and with its sharp end directed posterad in Ps. anfracta ); (3) the inferior appendages are each with the ventral lobe of its coxopodite slightly produced in a short, blunt lobe (each is strongly produced ventroposterad in a triangular lobe, with its apex reaching the tip of the harpago in ventral view in Ps. anfracta ).

Adult. Length of each male forewing 14.0– 14.5 mm (n = 2). Body light brown, antennae, palps and legs light yellowish brown; forewings pale yellowish brown. In forewing, R1 running separately to margin, Fork I rooted, with R2 segregating from mid-length of discoidal cell and with its apex close to tip of R1; stalk of fork II 1.5 times as long as crossvein r, cross vein r-m very short ( Fig. 11F ).

Male. Anterior margins of segment IX produced forward into large rounded lobes, posteroventral margins strongly convex in lateral view ( Fig. 11A ); median dorsal process of segment IX indistinguishably fused with segment X, forming a long, broad hooded dorsal process of X ( Fig. 11B ), in dorsal view, this hood about 2 times as long as its basal width, evenly narrowing to truncate apex, with small triangular projection on each lateral margin near base ( Fig. 11B arrow), and pair of long horn-like lateral processes produced from dorsal process of X basoventrally in lateral view ( Figs. 11A ). Ventral processes of X (= intermediate appendages?), forming pair of sclerotized, broad crescentic structures, each with its sharp end directed anterad and with short spine on each dorsal margin near middle, visible in both lateral and dorsal views ( Figs. 11A. 11B ). Preanal appendages long, lanceolate, each broadest at basal 2/3, tapering gradually to apex ( Fig. 11A ). Inferior appendages each with broad coxopodite, 1.5 times as long as wide in lateral view, each apicoventral lobe short and blunt ( Figs. 11A arrow, 11C arrow). Harpagones each having broad base and narrow apex, nearly 2 times as long as its basal width in lateral view, but short and stout with tips broadly rounded in ventral aspect and each bearing numerous short, black teeth apically ( Figs. 11A, 11C ). Phallus generally tube-like, phallobase long, cylindrical, slightly decurved and enlarged apicoventrally; phallicata

about 1/3 length of phallobase ( Fig. 11D ), with semi-membranous, apex round in lateral view (11D), bilobed in ventral view (11C); one pair of paramere spines, short and stout ( Fig. 11C ).

Holotype male. PR CHINA: Zhe-Jiang Province : City of Tai Zhou, Lin-hai County, Kuo-cang-shan [Mt.], N28.83, E120.98, alt. 450 m, 5 May 2016, Coll. Xu Ji-h. Paratypes. Same data as holotype, 1 male.

Etymology: Latin, longicornis , adjective meaning “longhorned,” referring to the paired horn-like lateral projections of the dorsal process of tergum X.

Distribution: Oriental Region, southeastern of China.

Figures

FIGURE 11. Psilotreta longicornis Yang & Morse, sp. n., male. 11A–11D, genitalia: 11A, left lateral; 11B, dorsal; 11C, ventral; 11D, phallus, left lateral. 11F, Right forewing, dorsal.