Arrenurus (Truncaturus) isikliensis Boyaci & Ozkan 2004

Arrenurus (Truncaturus) isikliensis Boyaci & Özkan, 2004

(Figs. 8A – F)

Material examined: No. HLJ-AR-1996081901, Hulan River, Yichun City, Heilongjiang Province, China (46°54′ N, 128°11′ E; alt. 230 m), 19-VIII-1996, Daochao Jin leg. Paratype, 0/0/0,

Description. Male (n=1): Idiosoma L 704 (including petiole), W 399, L/W ratio 1.8; anterior margin of idiosoma round, and wider than the posterior margin; dorsal shield W 304; distance between the eyes 152. Dorsal furrow posteriorly narrowed (Fig. 8B). D 4 on wide round humps (Fig. 8C). Cx-IV median suture lines much wider than the other coxae and posterior edges nearly straight. The tips of Cx-I and Cx-II moderately beyond the anterior margin of idiosoma (Fig. 8A). Gb approximately “U” shaped, ACG medium L 114, Gb–Cx-IV, 214; Gb–Gp, 33; Gb–Ep, 578 (Fig. 8A). Ap with five pairs of genital setae, of which two pairs located on the anterior edge near to Gp and three pairs located on the posterior edge (Fig. 8, A and C). L of palp segments: P-1, 27; P-2, 51; P-3, 49; P-4, 72; P-5, 38, P-2 with three ventral setae (Fig. 8D). L of I-L-1–6: 45, 83, 84, 120, 132, 132 (Fig. 8E); L of II-L-1–6: 38, 77, 87, 106, 114, 119; L of III-L-1–6: 43, 88, 98, 119, 127, 142; L of IV-L-1–6: 74, 133, 127, 217, 124, 143. Number of swimming setae: II-L-3 5, II-L-4 7, II-L-5 6; III-L-3 4, III-L-4 4, III-L-5 6; IV-L-3 6, IV-L-4 7 (including four short swimming setae on the spur), IV-L-5 6 (Fig. 8F).

Habitat. Rivers.

Remarks. The specimen from China shows general conformity with that from Turkey in the following features: Cx-IV median suture lines much wider than other coxae, posterior suture lines nearly straight, the tips of Cx-I and Cx-II moderately beyond the anterior margin of idiosoma, and the same structure of the genital area, and constitutes the first record of A. (T.) isikliensis Boyaci & Özkan, 2004 for the Chinese fauna (Boyaci & Özkan 2004).

However, the two populations are slightly different in the following: (1) P-2 with three dorsal setae in the Chinese specimen, but P-2 with seven dorsal setae in the one from Turkey. (2) The number of swimming setae on IV-L is larger in the Chinese specimen than Turkish. The differences observed can be due to geographical variation.

The Chinese specimen is also similar to Arrenurus (Truncaturus) viktorovi (Tuzovskij 2020) from North America. However, the main differences are in the following points: (1) The Ap is relatively long and narrow in the Chinese specimen, but the Ap is wider and round in the North American species. (2) Cauda is developed, but the petiole is not obvious in the Chinese specimen while the cauda is shorter and with a short petiole in A. (T.) viktorovi.