Monatractides oxystomus (K. Viets, 1935)

(Figs. 28E, 29E, 30B, Tab. 4)

Atractides oxystomus K. Viets 1935: 571.

Material examined. Malaysia, Borneo, Kipungit River, Poring Hot Springs, Mt Kinabalu, 6º02.776 N, 116º41.432 E, 568 m asl., 15.ix.2012 Smit 1/0/0 (mounted); Kibamabangan River, at waterfall, Crocker Range, 5º51.280 N, 116º08.417 E, 433 m asl., 18.ix.2012 Smit 0/1/0.

Compared material

Monatractides oxystomus (K. Viets, 1935): Lectotype ♀, here designated, SMF 4361 Torrenticola oxystoma ♀, type, K.Viets 47777, Java, Tjibodas, 1400 m, Kali Tjiwalen, 13.7.1929. Paralectotype ♀, on the same slide, here designated.

Monatractides tobaensis (K. Viets, 1935): Lectotype ♂, here designated, SMF 4509 Torrenticola tobaensis ♂, type, K.Viets 47804, Sumatra, Toba-Meer, 5 m, 8.4.1929. Paralectotype ♀, on the same slide, here designated.

Morphology

Male. General features —Idiosoma elongated-oval; shoulder platelet elongated (shoulder/frontal plate L ratio 2.0); frontal margin medially with large anterolaterally pointed apodemes; Cxgl–4 located far anteriorly, near tips of Cx-I; gnathosomal bay V-shaped, three pairs of knob-like protrusions at the lateral margins of gnathosomal bay; medial margin of Cx-II/III moderately long; genital field subrectangular; ejaculatory complex: proximal and distal arms well developed, carina anterior long, proximal chamber small (Fig. 30B); suture line of Cx-IV distinct, originating from lateral edge of genital field, laterally curved; line of primary sclerotization close to posterior margin of genital field; excretory pore and Vgl–2 well separated from the line of primary sclerotization, Vgl–2 posterior to excretory pore; gnathosoma with long dorsal apodemes, rostrum truncated; distal margin of P-3 and P-4 medially and laterally with several pointed extensions; P-4 with two ventral setae, one very long and away from distal edge.

Remarks. The male specimen from Kipungit River agrees well in general morphology with Monatractides oxystomus (K. Viets, 1935), a species originally described from Sumatra (K. Viets 1935) based on two females. The male was described by Lundblad (1971) from Central Java.

Monatractides oxystomus seems to be most similar to M. tobaensis (K. Viets, 1935), a species decribed from Toba Lake, in N Sumatra from at depth of 5 m (K. Viets 1935). The main difference between M. macroporus and M. tobaensis concerns the gnathosomal bay, characteristically V-shaped in the both species: in M. oxystomus three pairs of knob-like protrusions laying at the lateral margins of gnathosomal bay, while they are lacking in M. tobaensis. However there is one another important difference between these two species—the presence of swimming setae on the legs II–IV in M. tobaensis. The presence of swimming setae on legs was mentioned by K.Viets in the original description of M. tobaensis and its confirmed by our re-examination of the holotype of M. tobaensis. The numbers of swimming setae are as follows: II-L-4, 1; II-L-5, 1; III-L-4, 1; III-L-5, 1; IV-L-4, 1; IVL-5, 1. This is the second species of the genus characterized by the presence of swimming setae on legs. Recently, Pešić & Smit (2014) erected a new subgenus, Vietsclio, to accommodate Monatractides uniscutatus (K. Viets, 1925), a species known from Cameroon (K. Viets 1925) and Ghana (Pešić & Smit 2014). The latter species can easily be distinguished from M. tobaensis due to the anterolateral platelets fused with the large dorsal plate forming an undivided dorsal shield. Therefore we propose to shift M. tobaensis to the subgenus Vietsclio Pešić & Smit, 2014.

Distribution. Sumatra (“ Atractides oxystomus ” K. Viets 1935), Java (“ Torrenticola oxystoma ” Lundblad 1971), Thailand (Pešić & Smit 2009b). New for Borneo.