Monatractides (Monatractides) rivulus, Pešić, Vladimir & Smit, Harry, 2012

Pešić, Vladimir & Smit, Harry, 2012, Second contribution to the knowledge of water mites of the genus Monatractides K. Viets (Acari: Hydrachnidia, Torrenticolidae) from New Guinea, with descriptions of three new species, Zootaxa 3350, pp. 46-57 : 55

Monatractides (Monatractides) rivulus sp. nov.

( Fig. 8A–G )

Type series. Holotype, male, dissected and slide mounted, Indonesia, New Guinea, West Papua province, small stream ca. 2.5 km S of Mokwam, 08.xi.2011, 1˚ 05.881 S, 133˚ 54.272 E, alt. 1612 m asl. Paratypes: 2/0/0, same data as holotype, one male dissected and slide mounted.

Diagnosis (Female unknown). Idiosoma elongated (dorsal shield L/W ratio 1.6); frontal plates broad (L/W ratio 1.5–1.9); shoulder plates swollen anteriorly; the area of primary sclerotization of the dorsal plate with four dorsoglandularia; capitular bay slender (L/W ratio 2.9–3.1); medial suture line of Cx-2+3 relatively long (100 μm); genital field relatively slender (L/W ratio 1.3–1.4); posterior suture line of Cx-4 well accentuated and directed posterolaterally; excretory pore posterior to the line of primary sclerotization, Vgl-2 posterior and well separated to excretory pore; distal margins of P-2 and -3 without denticles, P-4 ventral hairs small, inserted more distally; I-L-6 relatively stout (L/H ratio 2.6–2.7).

Description. Male (holotype, in parentheses paratype): Idiosoma: (ventral view: Fig. 8B ) L 997 (988), W 650 (625); dorsal shield ( Fig. 8A ) L 838 (809), W 525 (514), L/W ratio 1.6 (1.57); dorsal plate 766 (750); shoulder plate L 247–250 (231–244), W 97–98 (91–97), L/W ratio 2.55 (2.5–2.6); frontal plate L 143–148 (153–158), W 94–96 (84–87), L/W ratio 1.52–1.54 (1.76–1.88); shoulder/frontal plate L ratio 1.67–1.75 (1.5–1.6); capitular bay L 186 (183), W 60 (62), L/W ratio 3.1 (2.9); Cx-1 total L 345 (341), Cx-1 medial L 159 (156), Cx-2+3 medial L 102 (102); ratio Cx-1 L/Cx-2+3 medial L 3.4 (3.3); Cx-1 medial L/Cx-2+3 medial L 1.6 (1.5); genital field L/W 206 (202)/150 (153), L/W ratio 1.37 (1.32), ejaculatory complex ( Fig. 8F ) L 270 (244); distance genital field–excretory pore 203 (203), genital field–caudal idiosoma margin 331 (328); capitulum ( Fig. 8C ) ventral L 220 (206); chelicera total L 232 (237); palp ( Figs. 8D–E ) total L 235 (229), dL: P-1, 34 (34); P-2, 66 (66); P-3, 48 (45); P-4, 65 (62); P-5, 22 (22); L P-2/P-4 ratio, 1.02 (1.06); L I-4–6 ( Fig. 8G ): 139 (135), 138 (137), 140 (140); I-L-6 L/ H ratio, 2.6 (2.7)

Female. Unknown.

Etymology. Named for living in a small stream.

Discussion. Due to the elongated idiosoma (e.g., dorsal shield L/W> 1.5), the broad frontal platelets (L/W 1.5–1.9), dorsal shoulder plates swollen anteriorly, relatively long suture line of Cx-2+3 (L 100 μm) and a moderately elongated genital field (L/W ratio 1.3–1.4), Monatractides rivulus sp. nov. can be easily distinguished from the other members of the M. macroporus species-complex.

Distribution. New Guinea (West Papua province); only known from the locus typicus ( Fig. 9B ).

Figures

FIGURES 8 A – G. Monatractides rivulus sp. nov., male, small stream ca. 2.5 km S of Mokwam: A = dorsal shield; B = ventral shield; C = capitulum; D = palp, medial view; E = palp, lateral view; F = ejaculatory complex; G = I-L- 4 – 6. Scale bars = 100 μm.

FIGURES 9 A – C. A. Stream ca. 3 km S of Mokwam, locus typicus of Monatractides magnus sp. nov. and M. neoaustralicus sp. nov. B. Stream ca. 2.5 km S of Mokwam, locus typicus of M. rivulus sp. nov. C. Stream Ilik near Lake Gita, sampling site of M. magnus sp. nov. Photos. H. Smit.