Monatractides longiventris ( K. Viets, 1939 )

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 : 10-13

Monatractides longiventris ( K. Viets, 1939)

( Figs. 41–52 )

syn. Torrenticola tranversalis ( Lundblad, 1941a) – Lundblad 1971: 317.

Material. Thailand: Stream near Haewsai Waterfall, Nam Nao NP, 425 m asl, 16.xi.2007, 16° 40.668 N 101° 41.856 E, leg Smit 3/7/0 (3/2/0 mounted).

Morphology. Male (Haewsai Waterfall, n=2): Idiosoma (ventral view: Fig. 42 ) L 625–669, W 450–463; dorsal shield ( Fig. 41 ) L 519–544, W 381–400, L/W ratio 1.36; dorsal plate L 494–500; shoulder plate L 134–150, W 47–53, L/W ratio 2.8–2.85; frontal plate L 103, W 45–50, L/W ratio 2.1–2.3; shoulder/frontal plate L ratio 1.3–1.5; capitular bay L 132–144, W 39–47, L/W ratio 2.8–3.7; Cx-1 total L 244–253, Cx-1 medial L 109–111, Cx-2+3 medial 66–73; ratio Cx-1 L/Cx-2+3 medial L 3.5–3.7; Cx-1 medial L/Cx-2+3 medial L 1.5–1.7; genital field L/W 123–128/103, L/W ratio 1.2–1.24, ejaculatory complex ( Fig. 46 ) L 166–167; distance genital field–excretory pore 130–142, genital field–caudal idiosoma margin 180–200; capitulum ( Figs. 43 ) ventral L 160–163; chelicera L 173–182; palp ( Fig. 44–45 ) total L 175–181, L and %L (given as % of total L): P- 1 24–29 (13.7–16.0), P-2 50–53 (28.6–29.3), P-3 33–35 (18.2–20.0), P-4 46 (25.4–26.3), P-5 20 (11.1–11.4); P-2/P-4 ratio 1.09–1.15; L I-Leg-4-6: 82–85, 85–88, 88–90.

Female (Haewsai Waterfall, n=2): Idiosoma (ventral view: Fig. 48 ) L 691–706, W 491–503; dorsal shield ( Fig. 47 ) L 606–612, W 400–420, L/W ratio 1.44–1.53; dorsal plate L 563–569; shoulder plate L 145–159, W 47–56, L/W ratio 2.8–3.1; frontal plate L 112–113, W 53–56, L/W ratio 2.0–2.1; shoulder/frontal plate L ratio 1.3–1.4; capitular bay L 145–153, W 44–47, L/W ratio 3.1–3.5; Cx-1 total L 245–256, Cx-1 medial L 100–103, Cx-2+3 medial 52–58; ratio Cx-1 L/Cx-2+3 medial L 4.2–4.9; Cx-1 medial L/Cx-2+3 medial L 1.72–1.98; genital field L/W 144–150/129–131, L/W ratio 1.1–1.16; distance genital field–excretory pore 177–182, genital field–caudal idiosoma margin 238–253; capitulum ventral L 168–176; chelicera L 190–205; palp ( Fig. 49 ) total L 180–184, L and %L (given as % of total L): P- 1 24–26 (13.3–14.1), P-2 53–55 (29.4–30.0), P-3 36 (19.6–20.0), P-4 47 (25.5–26.1), P-5 20 (10.9–11.1); P-2/P-4 ratio 1.13–1.17; L I-Leg-4- 6: 88–92, 92–94, 89–90.

Additionally we give the measurements for specimens suspected to represent the juvenile male of M. longiventris : Male: Ventral shield ( Fig. 52 ) L 613, W 431, dorsal shield ( Fig. 51 ) L 528, W 353, L/W ratio 1.5; dorsal plate 481; shoulder plate L 140, W 53, L/W ratio 2.6; frontal plate L 103, W 55, L/W ratio 1.9; shoulder/frontal plate L ratio 1.36; capitular bay L 152, W 47, L/W ratio 3.2; Cx-1 total L 250, Cx-1 medial L 98, Cx-2+3 medial L 78; genital field L/W 119/100, L/W ratio 1.19, ejaculatory complex L 162; gnathosoma ventral L 165; chelicera L 194; dorsal lengths (P-2-5): P-2 52, P-3 38, P-4 47, P-5 20; P-2/P-4 ratio 1.1; shape and setation as given for adult male; L I-Leg-4-6: 89, 89, 92.

Remarks. The specimens from Thailand agree well with the descriptions given by Lundblad (1967, 1969, 1971) for male and female specimens of M. transversalis (syn. to M. longiventris ), and female specimen of M. longiventris . This species is characterized by the medial suture line of Cx-2+3 relatively long in both sexes, capitulum with elongated, slender rostrum, P-4 without ventral denticles and a generally slightly accentuated posterior suture line of Cx-4. A difference is found in the slightly shorter medial suture line of Cx-2+ 3 in our female specimens.

Distribution. Burma (“ Torrenticola transversalis ” Lundblad 1941 ), Indonesia. New for Thailand.

Figures

FIGURES 41 – 46. Monatractides longiventris (K. Viets), male, Haewsai Waterfall: 41 = dorsal shield; 42 = idiosoma, ventral view; 43 = capitulum; 44 = palp (P- 1 missing), medial view; 45 = palp, lateral view; 46 = ejaculatory complex. Scale Bars = 100 µm.

FIGURES 47 – 50. Monatractides longiventris (K. Viets), female, Haewsai Waterfall: 44 = dorsal shield; 48 = idiosoma, ventral view; 49 = palp, medial view; 50 = anterodorsal portion of ventral shield. Scale Bars = 100 µm.

FIGURES 51 – 52. Monatractides longiventris (K. Viets), female, Haewsai Waterfall: 51 = dorsal shield; 52 = idiosoma, ventral view. Scale Bars = 100 µm.