Pentachares sinensis Li & Guo, 2022

Li, Hai-Tao, Jin, Dao-Chao, Yi, Tian-Ci & Guo, Jian-Jun, 2022, Contributions to the knowledge of Eylaoidea (Acari: Hydrachnidiae) from China, European Journal of Taxonomy 787 (1), pp. 53-70 : 61-66

Pentachares sinensis Li & Guo gen. et sp. nov.

urn:lsid:zoobank.org:act:EAE7CCA4-5C4C-410E-B226-09B3FC6D913D

Figs 6–9

Diagnosis

Capitulum attached to a long tubular extension of integument; palp five-segmented, P-V attached to membranous protuberance at medioventral surface of P-IV, heavy seta and a pair of setae at distal end; dorsum without sclerites except for the frontal plate; on frontal plate, median eye invisible, rod-like O 1 and A 1 sitting at anterior part, A 2 at the middle of eye capsules, bifurcated O 2 near the middle of posterior part; 50–60 acetabula per side of genital field; excretory pore with a sclerotized ring; legs without swimming setae, claws simple.

Etymology

Named after the country where the specimen collected. “Sina-” means China.

Type material

Holotype CHINA • ♀; Guangdong Province, Xiangtoushan National Nature Reserve ; 23°16′14″ N, 114°22′14″ E; 491 m a.s.l.; 24 Aug. 2019; Min Ao & Hai-Tao Li leg.; water depth 5–10 cm, located at the top of a hill, with organic detritus, dead wood and leaves on the bottom; GUGC, slide No. GD-LI-20190801 .

Description

Female (n = 1)

BODY. Amber in color, lateral eyes red, gnathosoma invisible in dorsal view when alive ( Fig. 6 ). Idiosoma extremely soft and extensible, integument papillate. Dorsum without sclerites in addition to frontal plate ( Fig. 7A ). Gnathosoma porous, in the ventral view rounded, rostrum relatively short; mouth disk with a loop of fine setae; porous basal segment of chelicera relatively large, proximal part of cheliceral stylet connected with basal segment vertically ( Fig. 7B ). Anterior part of frontal plate longer than eye capsule region; anterior margin concave, sclerotized inward; median eye invisible; O 1 rod-like and terminal expanded; A 2 at the middle of eye capsules; O 2 on the convex lateromedial plate and bifurcated; posterior part of frontal plate long, lateral margins covered by small tubercles densely; posterior margin straight; keel approximately as long as the frontal plate ( Fig. 7C ).

PALP. Five-segmented; P-I without seta; P-II with one dorsal and 3–4 ventral setae; a dorsodistal and 2 ventrolateral setae on P-III; P-IV with three ventral setae and one lateral heavy seta; P-V attached to a membranous protuberance at medioventral surface of P-IV, and bearing three setae at distal end ( Fig. 8A–B ).

COXAE. Cx-I inner-apical angles connected by a narrow bridge. Cx-I anterior margins concave, with uniformly stout setae. E 1 and E 2 on the membranous interspace between coxal groups. Cx-III triangular; Cx-IV elongated and triangular; all coxae porous ( Fig. 8C ).

GENITALIA. Genital field with 50–60 acetabula per side, acetabula inverted teardrop-shaped; gonopore with a slightly sclerotic plate with fine setae surrounded; a pair of elevated, longish sclerites with two apical setae behind gonopore; excretory pore with a sclerotized ring ( Fig. 8C ).

LEGS. With numerous stout setae except by the swimming setae, terminal segments of all legs with a loop of short setae; claws simple ( Fig. 9A–D ).

Male

Unknown.

Measurements

Idiosoma 2083 in length (with gnathosoma not extended), 1384 in width; protrusible membrane length 291 (flexibility maybe leading to inaccuracy); ACG length 368 (from anteromedial to posteromedial corner), PCG length 451 (from anteromedial to posteromedial corner); ocular plate 388 in length (from anteromedial to posteromedial corner), anterior part length 90, eye capsule region 49 in length, 114 in width, keel length 346; chelicera length 281; infracapitulum 154 in length (from the middle of infracapitulum furrow to rostrum); excretory pore length 71, sclerotic ring 81; dorsal lengths of palp segments: P-I 18, P-II 63, P-III 27, P-IV 39, P-V 33, P-IV heavy seta length 35, P-V apical seta length 23; dorsal lengths of leg segments: I-L-1 66, I-L-2 236, I-L-3 164, I-L-4 147, I-L-5 164, I-L-6 130. II- L-1 67, II-L-2 235, II-L-3 155, II-L-4 142, II-L-5 160, II-L-6 142. III-L-1 71, III-L-2 217, III-L-3 138, III-L-4 137, III-L-5 177, III-L-6 139. IV-L-1 62, IV-L-2 264, IV-L-3 184, IV-L-4 199, IV-L-5 218, IV- L-6 172.

Remarks

Pentachares sinensis Li & Guo gen. et sp. nov. with five-segmented palp is clearly distinguished from other species of the subfamily Rhyncholimnocharinae , but similar to Laterolimnochares huangshanensis Jin, 1999 and Limnochares spinosa Smit & Pesic, 2014 . Pentachares sinensis Li & Guo gen. et sp. nov. differs from La. huangshanensis in the following aspects: 1) with a protrusible tube of soft integument in P. sinensis Li & Guo gen. et sp. nov., while without in La. huangshanensis; 2) body color amber in P. sinensis Li & Guo gen. et sp. nov., while pink in La. huangshanensis; 3) O 1 rod-shaped in P. sinensis Li & Guo gen. et sp. nov., while pectinate in La. huangshanensis; 4) terminal heavy seta of P-V smooth in P. sinensis Li & Guo gen. et sp. nov., while feathered in La. huangshanensis; and 5) the setae on coxae short in P. sinensis Li & Guo gen. et sp. nov., but long in La. huangshanensis. Pentachares sinensis Li & Guo gen. et sp. nov. differs from Li. spinosa : 1) with a protrusible tube of soft integument in P. sinensis Li & Guo gen. et sp. nov., while without in Li. spinosa ; 2) O 1 and O 2 not smooth in P. sinensis Li & Guo gen. et sp. nov., but smooth in Li. spinosa ; 3) terminal heavy seta of P-IV smooth in P. sinensis Li & Guo gen. et sp. nov., but feathered in Li. spinosa ; and 4) the number of acetabula 50–60 in P. sinensis Li & Guo gen. et sp. nov., while only 40–50 in Li. spinosa .

Figures

Fig. 6. Pentachares sinensis Li & Guo gen. et sp. nov., holotype, ♀ (GUGC GD-LI-20190801). Dorsal view, alive.

Fig. 7. Pentachares sinensis Li & Guo gen. et sp. nov., holotype, ♀ (GUGC GD-LI-20190801). A. Idiosoma, dorsal view. B. Gnathosoma. C. Frontal plate. Scale bars = 200 μm.

Fig. 8. Pentachares sinensis Li & Guo gen. et sp. nov., holotype, ♀ (GUGC GD-LI-20190801). A. Palp, ventral view. B. Palp, lateral view. C. Idiosoma, ventral view. Scale bars = 200 μm.

Fig. 9. Pentachares sinensis Li & Guo gen. et sp. nov., holotype, ♀ (GUGC GD-LI-20190801). A. I-L- 1–6. B. II-L-1–6. C. III-L-1–6. D. IV-L-1–6. Scale bar = 200 μm.