Arrenurus (Arrenurus) ancoralis Zheng & Guo, 2021

Zheng, Yulin, Gu, Xinyao, Guo, Jianjun & Zhang, Runzhi, 2021, Two new species and one new record species of genus Arrenurus Dugès, 1834 (Acari, Hydrachnidia, Arrenuridae) from China, Zootaxa 5072 (1), pp. 63-72 : 65-67

Arrenurus (Arrenurus) ancoralis Zheng & Guo sp. nov.

( Figs. 1–3 )

Material examined: Holotype male, No. GD-AR-2002100301, stream, Dinghushan National Nature Reserve , Zhaoqing City, Guangdong Province, China (23°10’N, 112°31’E; alt. 1000 m), 3-X-2002, Jianjun Guo leg. Paratype, 0/1/0, No. GD-AR-2002100302, same data as holotype.

Diagnosis. D 3 on big humps and each with a small protrusion bearing D 3 gland; petiole well-developed, the median somewhat contracted and the end slightly enlarged. Ligulate process extending beyond posterior margin of petiole, and approximately triangle-shaped and nearly straight posteriorly in dorsal view.

Description. Male (n=1): Idiosoma L 1126 (including petiole), W 738, L/W ratio 1.5. Anterior margin of idiosoma slightly concave. Dorsal furrow incomplete, and not reaching to the middle of the pygal lobe’s dorsum; dorsal shield W 419, anterior margin nearly round ( Fig. 1B ). Dorsal humps well developed, directed upward, and with a small protrusion bearing D 3 gland near the top of each. Petiole well-developed, L 114, the median somewhat narrowed, and the end slightly widened in dorsal view; ligulate process extending beyond posterior margin of petiole, approximately triangle-shaped and almost straight posteriorly ( Fig. 1C ). ACG medium L 156; Gb–Cx-IV, 532; Gb–Gp, 593; Gb–Ep, 845; Cx-IV posterior angles undeveloped ( Fig. 1A ). Inverted T-shaped cuticular structure between the glands of D 4 undeveloped, only with horizontal ridge ( Fig. 1D ); Ap evenly extending from Gp to the sides of the body ( Fig. 1A, 1C ). L of palp segments: P-1, 30; P-2, 65; P-3, 53; P-4, 97; P-5, 67; P-2 with three dorsal setae; P-3 medially with two setae near anterior margin ( Fig. 1E ). L of I-L-1–6: 52, 124, 133, 164, 152, 179 ( Fig. 2A ). L of II-L-1–6: 56, 115, 135, 147, 161, 196. L of III-L-1–6: 54, 116, 150, 180, 174, 199. L of IV-L-1–6: 144, 200, 255, 342, 129, 114. Spur of IV-L-4 more than the half length of IV-L-5. Number of swimming setae: II-L-3 3, II-L-4 7, II-L-5 6; III-L-3 8 ( Fig. 2B ), III-L-4 9, III-L-5 7; IV-L-3 14 ( Fig. 2C ), IV-L-4 16 (including five short swimming setae on the spur), IV-L-5 9 ( Fig. 2D ).

Female (n=1): Female (n=1): Idiosoma L 1194, W 1042, L/W ratio 1.1; dorsal furrow complete; D 1 glands on the dorsal humps ( Fig. 3B and C ). Cx-I and Cx-II not extending beyond anterior margin of idiosoma. Medial margin of Cx-IV longer than medial margin of Cx-III. Posteromedial corner of Cx-IV rounded. Gp approximately heartshaped, L 137 and W 152 and flanked by relatively long wing shaped Ap. ACG medium L 190; Gb–Cx-IV, 495; Gb–Gp, 609; Gb–Ep, 944. Ap short, and narrow laterally towards the distal ( Fig. 3A ); L 137 and W 152; ( Fig. 3A ). L of palp segments: P-1, 17; P-2, 76; P-3, 55; P-4, 118; P-5, 57. P-2 medially with two setae near anterior margin ( Fig. 3D ). L of I-L-1–6: 52, 113, 156, 179, 167, 171 ( Fig. 3E ). L of II-L-1–6: 72, 144, 168, 197, 171, 190. L of III-L-1–6: 66, 132, 169, 173, 179, 189. L of IV-L-1–6: 120, 217, 217, 266, 194, 126. Number of swimming setae: II-L-3 3, II-L-4 8, II-L-5 7; III-L-3 8, III-L-4 9, III-L-5 7; IV-L-3 17, IV-L-4 15, IV-L-5 14 ( Fig. 3F ).

Habitat. Pool in the stream bed with dead branches and rotten leaves.

Etymology. Derived from the Latin word “ancorale” (anchor). In this new species, D 3 gland protrusion looks like an anchor.

Remarks. The new species is very similar to Arrenurus (Arrenurus) cuspidator Müller, 1776 ( Viets 1936) in general shape of idiosoma and petiole, but differs from the new species in the following points: (1) Dorsal humps directed upwards in the new species, but is directed towards the anterior margin of idiosoma in A. (A.) cuspidator . (2) Hyaline membrane is not obvious in the new species, but obvious in A. (A.) cuspidator . (3) Caudal humps with V 2 and V 3 are developed, beyond the posterior margin of the body in the new species, but undeveloped in A. (A.) cuspidator . (4) The humps of D4 are wider in the new species than in A. (A.) cuspidator .

The new species is close to Arrenurus (Arrenurus) antalyensis Gülle, Boyaci & Gülle, 2011 (Yunus et al. 2013) collected from Turkey, but they differ from each other by the following: (1) The petiole end is slightly enlarged in the new species, but obviously enlarged in A. (A.) antalyensis . (2) Cx-I and Cx-II not extending to the anterior margin of idiosoma in the new species, but extending beyond the anterior margin of idiosoma in A. (A.) antalyensis . (3) Dorsal humps are directed upwards in the new species, while titled forwards the anterior of idiosoma in A. (A.) antalyensis . (4) The pygal lobes are well-developed in the new species, but small in A. (A.) antalyensis ; (5) Ligulate process is relatively short in the new species, but elongated in A. (A.) antalyensis .

Figures

FIGURE 1. Arrenurus (Arrenurus) ancoralis, Zheng & Guo sp. nov., male:A = Idiosoma, ventral view; B = Idiosoma, dorsal view; C = Idiosoma, dorsolateral view; D = Detail of petiole; E = Palp.

FIGURE 2. Arrenurus (Arrenurus) ancoralis, Zheng & Guo sp. nov., male: A = I-Leg; B = II-Leg; C = III-Leg; D = IV- Leg.

FIGURE 3. Arrenurus (Arrenurus) ancoralis, Zheng & Guo sp. nov., female: A = Idiosoma, ventral view; B = Idiosoma, dorsal view; C = Palp; D = I-Leg; E = IV-Leg.