Oecetis (Pleurograpta) spinellosa, 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 : 149-151

Oecetis (Pleurograpta) spinellosa sp. n. Yang & Hu

( Figs. 6 , 7D, 7F )

Diagnosis. This new species belongs to the Oecetis (Pleurograpta) testacea Group in which the males have the last abdominal tergites with “Maschenplatten” ( Malicky 2005, or “honeycomb reticulation areas” of Yang & Morse 2000). The male resembles those of Oe. (Pl.) t. testacea ( Curtis 1834) (widely distributed in the Palearctic Region), Oecetis (Pl.) testacea kumanskii Yang & Morse 2000 ( Korea), Oe. (Pl.) tsudai Fischer 1970 ( Japan), and Oe. (Pl.) palamedes Malicky 2005 (Indonesia-Sumatra) in the distribution of honeycomb reticulation areas and the general shape of the genitalia. This new species, from Oriental China, differs from them in the following characters: 1) The posterolateral corners of the upper half of segment IX are not protruded backward, but instead each forms a vertical, elliptical region with its height 2 times its longitudinal length and densely covered with minute spines and setae ( Fig. 6A upper arrow; the posterodorsal corners of segment IX each protrudes in an acute triangle with minute spines in Oe. testacea kumanskii and protrudes in a rounded lobe almost without spines in Oe. t. testacea and Oe. palamedes); 2) the dorsal branch of each inferior appendage slopes backward forming a 60° angle with the basoventral branch and the apex of the dorsal branch is smooth, acute, and pointed upward (the dorsal branch is straight and points upward forming at least a 100° angle with the basoventral branch and the apex of the branch bears several stout teeth and is curved mesad in Oe. t. testacea, Oe. testacea kumanskii, Oe. tsudai, and Oe. palamedes); 3) the basoventral branch of each inferior appendage has a distinctive small mesodorsal seta-bearing chalaza ( Fig. 6A lower arrow; each inferior appendage is without a mesodorsal chalaza in the above four species); 4) the phallus has two long, identical paramere spines (the phallus has one long paramere spine and three short spines in Oe. t. testacea and Oe. testacea kumanskii, one long and one shorter spine in Oe. palamedes; phallic spines are unknown in Oe. tsudai). Tergum X is much longer in Oe. palamedes than in the other four species and the preanal appendages are not evident.

The females of Oe. tsudai and Oe. palamedes are unknown. The females of Oe. t. testacea and Oe. testacea kumanskii were illustrated by Kumanski (1991). The female of the new species can be distinguished from those of Oe. t. testacea and Oe. testacea kumanskii by the following characters: 1) The lamellae are well sclerotized, each quadrate in its basal half with the distal half narrowing to a finger-like process in lateral view ( Fig. 7D ; each lamella is a short or elongate lobe without a slender finger-like apical process in Oe. t. testacea and Oe. testacea kumanskii); 2) the gonopod plate is broader posteriorly and with a pair of rounded posterolateral corners in ventral view ( Fig. 7F ; the gonopod plate is nearly circular, broadest at midlength, narrowed and rounded anteriorly and posteriorly in Oe. t. testacea ; a ventral view of Oe. testacea kumanskii is not available).

Adult. Length of each male forewing 5.7–6.7 mm (n = 3), of each female forewing 6.0– 6.5 mm (n = 5). Head and thorax yellowish brown. Forewings hyaline, faintly yellowish; forks of veins and anastomosis lightly shaded with fuscous, veins of anastomosis aligned ( Fig. 6F ). Thick honeycomb reticulation areas covering terga V, VI, and VII in pairs, and an undivided honeycomb reticulation are covering tergum VIII.

Male genitalia. Segment IX longitudinally long ventrally, very short dorsally, anterior margins of pleura IX strongly produced forward in lateral view, posterodorsal corners each forming vertical, elliptical concavity with its height 2 times its longitudinal length and densely covered with minute spines and setae ( Fig. 6A upper arrow, 6B pos.cr.IX); preanal appendages slender, divergent, curved slightly downward, gradually slightly thicker apically. Upper part of tergum X ( Fig. 6B up.pt.X) single, rod-like, lower part of tergum X ( Fig. 6B lo.pt.X) composed of pair of flat, semimembranous lobes, each bearing few setae apically. Dorsal branch of each inferior appendage sloping backward forming 60° angle with basoventral branch, very broad in basal half with distal half gradually reducing to smooth, acute, triangular tip pointed upward ( Fig. 6A d .br.), in caudal view with basomesal region of dorsal branch set with many minute spines ( Fig. 6C arrow); basoventral branches of inferior appendages divergent, each with distal half finger-like and with blunt tip in ventral view ( Fig. 6 C-bv), in lateral view each with small triangular seta-bearing chalaza on upper surface near middle ( Fig. 6A lower arrow, 6C-bv arrow). Phallus asymmetrical, right piece of phallobase tall, well developed, with left piece much lower, its dorsal margin expanded outward, forming narrow longitudinal ridge (arrow); two long paramere spines essentially identical ( Fig. 6D ).

Female genitalia. Pleural region of segment IX produced outward, appearing as subvertical ridge in lateral view ( Fig. 7D left arrow); in ventral view, each side forming large plate, rounded at outer margin with median portion moderately concave ( Fig. 7F ). Dorsum IXc and segment X forming short anal tube, its bottom semimembranous with U-shaped cleft apically ( Fig. 7F ). Lamellae well sclerotized, broadly quadrate in basal half, each with its dorsolateral margin forming round, setose ridge ( Fig. 7D right arrow), distal half reduced to finger-like process in lateral view ( Fig. 7D ). Posterior margin of gonopod plate broader than anterior margin and slightly sinuate in ventral view ( Fig. 7F ). Internal part of gonopod VIII semimembranous, with its exposed portion short and rectangular in ventral view and triangular in lateral view ( Figs. 7D, 7F ). Diagonal striations on lower regions of pleura ( Fig. 7F arrow).

Holotype. Male ; CHINA: An-hui Province , Qi-men County, Li-xi Village, Qi-yang-keng, N29.52, E117.42, alt. 360 m, 14 Aug. 2001, Coll. Hu B-j. and Wang B-x . Paratypes. Same data as holotype, except Gu-niu-jiang Nature Preserve Shuang-he-kou, Tao-yuan-li stream, alt. 480 m, 25 May 2001, Coll. Wang B-x. and Yang W-f., 2 males, 11 females ; Same data as holotype, except Peng-long, Xiang-dong Village, alt. 380 m, 27 Sep. 2003, Coll. Sun C-h. and Shan L-n., 1 male .

Etymology. Latin, spinellosa , adjective, meaning “with many minute spines,” with reference to the basomesal region of the dorsal branch of each inferior appendage set with many minute spines.

Distribution. Found only at the type localities, Oriental Region, Southeast China.

Figures

FIGURE 6. Oecetis (Pleurograpta) spinellosa Yang & Hu, sp. n., male. 6A–6D, genitalia: 6A, left lateral; 6B, dorsal; 6C, left inferior appendage and phallus, caudoventral; 6C-bv, inferior appendages, ventral; 6D, phallus left lateral. 6F, Right forewing, dorsal.

FIGURE 7. Oecetis spp. n., female genitalia. 7A–7C, Oecetis (O.) discedens Yang & Morse, sp. n.: 7A, left lateral; 7B, dorsal; 7C, ventral. 7D, 7F, Oecetis (Pleurograpta) spinellosa Yang & Hu, sp. n.: 7D, left lateral; 7F, ventral.