Torrenticola schilthuizeni, Pešić & Smit, 2014

Pešić, Vladimir & Smit, Harry, 2014, Torrenticolid water mites (Acari: Hydrachnidia: Torrenticolidae) from Malaysian Borneo, Zootaxa 3840 (1), pp. 1-72 : 25-26

Torrenticola schilthuizeni n. sp.

( Figs. 15A–D , 16F , 17F )

Type series. Holotype female, dissected and slide mounted, Malaysia, Borneo , Kibamabangan River, Crocker Range, 5º 51.28 N, 116 º 08.417 E, alt. 433 m asl., 18.ix.2012 Smit.

Diagnosis (Male unknown). Idiosoma roundish (dorsal shield L/W ratio 1.2); Cxgl–4 subapical, only slightly posterior of Cx-I tips; P-2 with a laterally compressed, longish (> 30% of ventral margin), anteriorly directed ventrodistal extension; P-3 with a very long seta laterally at base of projection.

Description

Female. General features —Idiosoma roundish; gnathosomal bay U-shaped, proximally pointed; Cxgl–4 subapical, only slightly posterior of Cx-I tips; genital field pentagonal; suture lines of Cx-IV extending back beyond posterior margin of genital field, laterally curved; excretory pore away from the line of primary sclerotization, excretory pore slightly posterior from Vgl-2; gnathosomal rostrum long, ventral margin in lateral view slightly curved ( Fig. 15D ); P-2 slightly longer than P-4, P-2 ventral margin with a denticulation also in proximal half of the segment, distally with a laterally compressed, longish (>30% of ventral margin), anteriorly directed and apically serrated hyaline extension with and a very short, denticle-like seta laterally at base of projection; P-3 with a longish, subrectangular, apically serrated ventrodistal projection, and a very long seta laterally at base of projection; P-4 slender, with ventral tubercles pointed and separated, bearing one long and three short setae ( Fig. 15C ).

Measurements —Idiosoma (ventral view: Figs. 15B , 17F ) L 578, W 434; dorsal shield ( Figs. 15A , 16F ) L 448, W 362, L/W ratio 1.24; dorsal plate L 403; shoulder plate L 148, W 59–93, L/W ratio 2.4–2.5; frontal plate L 116, W 53–56, L/W ratio 2.05–2.2; shoulder/frontal plate L 1.28. Gnathosomal bay L 119, Cx-I total L 256, Cx-I mL 137, Cx-II+III mL 42; ratio Cx-I L/Cx-II+III mL 6.1; Cx-I mL/Cx-II+III mL 3.3. Genital field L/W 124/120, ratio 1.04; distance genital field-excretory pore 106, genital field-caudal idiosoma margin 153. Gnathosoma vL 291; chelicera total L 326; palp total L 238–239, dL/H, dL/H ratio: P-1, 28/25, 1.12; P-2, 71/47, 1.49; P-3, 55/39, 1.4; P-4, 68–69/20, 3.4; P-5, 16/11, 1.5; P-2/P-4 ratio 1.03.

Male: unknown.

Etymology. Named after Menno Schilthuizen, leader of the Mt Kinabula-Crocker Range expedition.

Discussion. Due to the Cxgl–4 subapical and P-2 ventral margin distally with a laterally compressed, anteriorly directed ventrodistal extension and a denticulation also in proximal half of the segment, the new species resembles Torrenticola tjiwalensis (K. Viets, 1935) and T. dentifera Wiles, 1991 . The latter species, originally described from Selangor, Peninsular Malaysia ( Wiles 1991), and later on found in South Korea ( Pešić et al. 2013b), is known only from the male sex. It can easily be distinguished from the new species in having a short ventral seta on P-3 and P-4 with long and broadly rounded distal seta. Torrenticola tjiwalensis (Java, Peninsular Malaysia, Borneo) resembles the new species in having a long ventral seta on P-3 (longer than P-3) but differs in a small, rudimentary flange ventrally on P-2 (see Wiles 1997). Further differences are found in a more elongated dorsal shield, excretory pore and Vgl-1 shifted more away from the line of primary sclerotization and a less shallow gnathosoma with a relatively more shortened rostrum in the female of T. tjiwalensis (see K. Viets 1935)

Habitat. Sandy/bouldery streams, shaded by rain forest ( Fig. 43C ).

Distribution. Borneo; known only from the locus typicus.

Subgenus Megapalpis Halbert, 1944

Figures

FIGURE 15A–D. Torrenticola schilthuizeni n. sp., holotype female, Kibamabangan River: A = dorsal shield; B = idiosoma, ventral view; C = palp, medial view; D = gnathosoma. Scale bars = 100 µm.

FIGURE 16A–F. Photographs of dorsal shield. A–B Torrenticola minuta (Lundblad, 1941): A = male, Kemantis stream; B = female, Great Lumotok stream. C–D T. neoindica n. sp., Mahua stream: C = male holotype; D = female paratype. E T. tjiwalensis (K. Viets, 1935), male, Mahua stream. F. T. schilthuizeni n. sp., female holotype, Kibamabangan River.

FIGURE 17A–F. Photographs of ventral shield. A–B Torrenticola minuta (Lundblad, 1941): A = male, Kemantis stream; B = female, Great Lumotok stream. C–D T. neoindica n. sp., Mahua stream: C = male holotype; D = female paratype. E T. tjiwalensis (K. Viets, 1935), male, Mahua stream. F T. schilthuizeni n. sp., female holotype, Kibamabangan River.

FIGURE 43A–D. Photographs of selected sampling sites: A—Mahua stream (type locality of Torrenticola kinabaluensis n. sp. and sampling site of Torrenticola borneoensis n. sp., T. sabahensis n. sp., T. minuta, T. neoindica n. sp., T. cf. pugionirostris, Monatractides longiventris, M. parviventris and M. morpheus n. sp.), B—Unnamed stream Bansadon Trail (type locality of Neoatractides uniscutatus n. sp. and sampling site of Torrenticola borneoensis n. sp., T. kinabaluensis n. sp., Monatractides cf. macroporus and M. parviventris). C—Kibamabangan River (type locality of Torrenticola schilthuizeni n. sp. and sampling site of Torrenticola borneoensis n. sp., T. kinabaluensis n. sp., T. minuta and T. neoindica n. sp., Monatractides cf. macroporus, M. oxystomus, M. parviventris and M. morpheus n. sp.). D—Kemantis stream (type locality of Torrenticola borneoensis n. sp., Neoatractides sundaensis n. sp. and Monatractides phantasos n. sp. and sampling site of T. minuta, Monatractides longiventris, M. parviventris and M. morpheus n. sp.). Photos. H. Smit.