Monatractides plumosa ( Wiles, 1989 )

Pesic, Vladimir & Smit, Harry, 2009, Water mites of the family Torrenticolidae (Acari: Hydrachnidia) from Thailand, Part II. The genus Monatractides K. Viets, Zootaxa 2012, pp. 1-27 : 23-24

Monatractides plumosa ( Wiles, 1989)

( Figs. 103–108 )

syn. Torrenticola pilosa Wiles, 1989 – Wiles 1999: 430.

Material. Thailand, Thorntip Waterfall, Kaeng Krachan NP, 29.xi.2007, 12° 50.952 N 99° 18.498 E, leg. Smit 0/1/0 (0/1/0 mounted).

Morphology. Female: Idiosoma (ventral view: Fig. 104 ) L 756, W 688; dorsal shield ( Fig. 103 ) L 631, W 531, L/W ratio 1.2; dorsal plate L 566; shoulder plate L 230, W 84, L/W ratio 2.7; frontal plate L 131, W 84, L/W ratio 1.6; shoulder/frontal plate L ratio 1.8; capitular bay L 81, Cx-1 total L 263, Cx-1 medial L 181, Cx- 2+3 medial 100; ratio Cx-1 L/Cx-2+3 medial L 2.6; Cx-1 medial L/Cx-2+3 medial L 1.8; genital field L/W 156/141, L/W ratio 1.1; distance genital field–excretory pore 178, genital field–caudal idiosoma margin 225. Capitulum long and narrow with pointed rostrum ( Fig. 105 ) ventral L 272; chelicera L 294; palp ( Figs. 106–107 ) total L 181, L and %L (given as % of total L): P-1 23 (12.7), P-2 60 (33.2), P-3 44 (24.3), P-4 39 (21.6), P-5 15 (8.3); P-2/P-4 ratio 1.54; palp with terminal tuft of setae obscuring P-5. L I-Leg-4-6 ( Fig. 108 ): 99, 91, 100; L IV-Leg-1-6: 120, 98, 131, 163, 169, 166.

Remarks. The specimen from Thailand agrees well with the description of M. pilosa given by Wiles (1989) for the specimens from the Tamen Negara rainforest in Malaysia. This species differs from M. plumosa ( Wiles, 1989) , described from N. Sulawesi, primarily in the more shallow, pointed capitular bay; longer setae on the palp and a considerable extended medial margin of Cx-4 behind the genital flap. Later on, Wiles (1999) found that the palp of the male specimens from Brunei is intermediate between M. pilosa and M. plumosa , and synonymised M. pilosa with M. plumosa .

In the original description Wiles (1989) mentioned the similarity of M. plumosa with M. cristatus ( Viets, 1916) and M. intermedia ( Cook, 1966) from Africa. Monatractides cristatus has P-4 considerably smaller than P-3 and P-2 as long as P-3 and P-4 combined, while M. intermedia has a considerably less plumose P-5.

Monatractides pilosa is similar to M. ceylonensis ( K.O. Viets, 1973) known from a single female specimen from Sri Lanka ( K.O. Viets 1973). However, Wiles (1989) did not mention the similarity with M. ceylonensis . Due to the shape of the palp, idiosoma and capitulum dimensions this species show a general conformity with M. plumosa . The variability of further specimens needs to be examined to clarify the taxonomy.

Distribution. Malaysia, Sulawesi (“ Torrenticola pilosa ” Wiles 1989 ). New for Thailand.

Figures

FIGURES 103 – 108. Monatractides plumosa (Wiles), female: 103 = dorsal shield; 104 = idiosoma, ventral view; 105 = capitulum; 106 = palp (P- 1 missing); 107 = palp; 108 = I-Leg- 5 - 6. Scale Bars = 100 µm.