Torrenticola siamis, Pesic & Smit, 2009

Pesic, Vladimir & Smit, Harry, 2009, Water mites of the family Torrenticolidae Piersig, 1902 (Acari: Hydrachnidia) from Thailand, Part I. The genera Torrenticola Piersig, 1896, Neoatractides Lundblad, 1941 and Pseudotorrenticola Walter, 1906, Zootaxa 1982, pp. 38-62 : 45

Torrenticola siamis sp. nov.

( Figs. 27–36)

Type series. Holotype: male, dissected and slide mounted in Hoyer's fluid. Thailand, Pong Creek crossing road to Muang Kong, Doi Chiang Dao, alt. 477 m, 22.xi.2007, 19° 24.774 N 98° 55.127 E, leg. Smit. Paratype: one female, same station and date, dissected and slide mounted in Hoyer's fluid.

Diagnosis. Median suture line of Cx-2+3 short; Cx-4 not extended posterior to genital field; male genital field rectangular, ejaculatory complex conventional in shape; deep capitulum with a short rostrum.

Description

Male: Idiosoma (ventral view: Fig. 28) L 638, W 469; dorsal shield ( Fig. 27) L 563, W 406, L/W ratio 1.4; dorsal plate 519; shoulder plate L 150, W 66, L/W ratio 2.3; frontal plate L 123, W 64, L/W ratio 1.9; shoul- der/frontal plate L ratio 1.2; gnathosomal bay L 113, Cx-1 total L 238, Cx-1 medial L 125, Cx-2+3 medial 78; ratio Cx-1 L/Cx-2+3 medial L 3.1; Cx-1 medial L/Cx-2+3 medial L 1.6; genital field L/W 141/103, L/W ratio 1.4, ejaculatory complex ( Fig. 29) L 189; distance genital field–excretory pore 119, genital field–caudal idiosoma margin 178; capitulum ( Fig. 30) ventral L 186; chelicera L 216; palp ( Figs. 34-35) total L 192, L and %L (in parentheses): P-1 20 (10.4), P-2 55 (28.7), P-3 36 (18.8), P-4 59 (30.7), P-5 22 (11.5); P-2/P-4 ratio 0.93; ventral projections of P-2 and P-3 blunt.

Female: similar to the male; the short postgenital area and caudal position of the excretory pore are due to the obviously juvenile age of the specimen (indicated by weak sclerotization and absence of eggs). Ventral shield ( Fig. 32) L 544, W 456; dorsal shield ( Fig. 33) L 494, W 394, L/W ratio 1.25; dorsal plate 450; shoul- der plate L 159, W 70, L/W ratio 2.3; frontal plate L 128, W 66, L/W ratio 1.9; shoulder/frontal plate L ratio 1.2; gnathosomal bay L 131, Cx-1 total L 244, Cx-1 medial L 113, Cx-2+3 medial 38; ratio Cx-1 L/Cx-2+3 medial L 6.4; Cx-1 medial L/Cx-2+3 medial L 3.0; genital field L/W 156/134, L/W ratio 1.2; capitulum ( Fig. 31) ventral L 203; chelicera L 256; palp ( Fig. 36) total L 208, L and %L (in parentheses): P-1 23 (11.1), P-2 58 (27.9), P-3 39 (18.8), P-4 64 (30.8), P-5 24 (11.5); P-2/P-4 ratio 0.91; shape and setation as in male.

Discussion. Due to the sub-apical Cxgl-4, a rectangular shape of the male genital field, a deep capitulum with a short rostrum and Cx-4 not extended posterior to genital field, Torrenticola siamis sp. nov. resembles T. retractipora (Lundblad) , known from a single male specimen from Burma. However, T. retractipora is a large species (e.g., ventral shield L/W 966/703, data from Wiles 1997) which can be easilly distinguished from T. siamis sp. nov. by the shape of the ejaculatory complex (similarly shaped ([see: Lundblad 1969] as in T. thailandicus sp. nov. [see below] vs. conventional in shape with well-developed proximal horns in T. siamis – compare Fig. 29 with Fig. 45) and a moderately long median suture line of Cx-2+3 (101µm, data taken from Wiles 1997).

Etymology. The species is named after Siam, the old name of Thailand.

Distribution. Known only from the type locality in Thailand.

Biology. Torrenticola siamis sp. nov. is probably a rhitrobiontic species.