Monatractides acutiscutatus (K. Viets, 1914)

Pešić, Vladimir & Smit, Harry, 2014, Torrenticolid water mites (Acari: Hydrachnidia: Torrenticolidae) from Ghana, Zootaxa 3820 (1), pp. 1-80 : 28-30

Monatractides acutiscutatus (K. Viets, 1914)

( Figs. 17A–F , 25A , 26A )

Atractides acutiscutatus K. Viets 1914: 17 .

New records. Ghana: Unnamed creek upstream Sagyimase, Atewa Hills, 6º 13.966 N, 0º 33.114 W, alt. 671 m asl., 28.ii.2013 Smit, 0/1/0 (mounted); Laboun River, downstream of falls, Kyabobo NP, 8º 19.836 N, 0º 35.487 E, alt. 342 m asl., 24.ii.2013 Smit 0/1/0 (mounted).

Morphology. Female. General features —Idiosoma elongated oval; shoulder platelets on each side fused with frontal platelets to form an elongated platelet ( Figs. 17A , 25A ); frontal margin medially with large anterolaterally pointed apodemes ( Fig. 17C ); Cxgl-4 located far anteriorly, near tips of Cx-I; gnathosomal bay moderately deep, narrow U-shaped; posterior suture line of Cx-IV well evident, originating from lateral edge of genital field and directed posterolaterally; genital field large and pentagonal; 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 ( Fig. 17B ); gnathosoma with long and slender dorsal apodemes, rostrum truncated ( Fig. 17E ); ventral and dorsal setae of P-2 and P-3 relatively strong and long, distal margin of P-3 and P-4 medially and laterally with several pointed extensions; P-4 swollen in distal half, with two ventral setae, one of which is very long and away from distal edge ( Fig. 17D ).

Measurements (from unnamed creek upstream Sagyimase, in parentheses specimen from Laboun River, n = 2)—Idiosoma (ventral view: Figs. 17B , 26A ) L 694 (783), W 525 (644); dorsal shield ( Figs. 17A , 25A ) L 598 (675), W 448 (563), L/W ratio 1.33 (1.2); dorsal plate L 559 (638); anterior plate (shoulder + frontal platelet) L 298–306 (341–359), W 70–72 (80–86), L/W ratio 4.2–4.3 (4.2–4.3). Gnathosomal bay L 117 (129), Cx-I total L 242 (288), Cx-I mL 125 (158), Cx-II+III mL 78 (92); ratio Cx-I L/Cx-II+III mL 3.1 (3.1); Cx-I mL/Cx-II+III mL 1.6 (1.7). Genital field L/W 148 (164)/144 (159), ratio 1.03 (1.03); distance genital field-excretory pore 197 (159), genital field-caudal idiosoma margin 223 (238). Gnathosoma vL 135 (168); chelicera total L 182 (217); palp total L 200 (220–222), dL/H, dL/H ratio: P-1, 22/22, 1.0 (25/26, 0.94); P-2, 51/37, 1.38 (61/44, 1.38); P-3, 40/31, 1.3 (45/ 35, 1.3); P-4, 54/20, 2.7 (58/23, 2.5); P-5, 33/12, 2.7 (31–32/14, 2.3); P-2/P-4 ratio 0.94 (1.04); dL of I-L-2-6: 63 (72), 71 (91), 85 (112), 84 (106), 88 (100); I-L-4–6 H 32 (37), dL/H I-L-6 ratio 2.7 (2.7).

Remarks. The two female specimens examined match the general morphology of M. acutiscutatus (K. Viets, 1914) . This species was described by K. Viets (1914) based on a single specimen (assigned to male with a question mark, apparently because he did not find the ejaculatory complex) from a stream near Manoka in Cameroon. No further record of this species was published after its original description and this is the first description of the female. Monatractides acutiscutatus can easily be distinguished from other African members of the genus by the shoulder and frontal platelets of each side being fused to each other. This character is also found in several other species of Monatractides : M. (M.) hesperia ( Lundblad, 1941) ( Colombia, Lundblad 1941), M. (M.) veracruzensis ( Cook, 1980) ( Mexico, Cook 1980) and M. (M.) sahuli Pešić & Smit, 2011 (New Guinea, Pešić & Smit 2011). For differences separating abovementioned species see Pešić & Smit (2011). K. Viets (1931) proposed the subgenus ‘ Rusetriella ’ for these species, which has been rejected by Wiles (1997) based on a phylogenetic analysis.

Distribution. Cameroon (K. Viets 1914), Ghana (first record).

Figures

FIGURE 17 A – F. Monatractides acutiscutatus (K. Viets, 1914), female (A, C – F—from unnamed creek upstream Sagyimase, B—from Laboun River): A = dorsal shield; B = idiosoma, ventral view; C = frontal margin of idiosoma, dorsal view; D = palp, lateral view; E = gnathosoma; F = I-L- 4 – 6. Scale bars = 100 Μm.

FIGURE 25 A – I. Photographs of dorsal shield. A Monatractides acutiscutatus (K. Viets, 1914), female, unnamed creek upstream Sagyimase. B – C M. convexiscutata (K. Viets, 1958), stream Asukuma: B = male, C = female. D – E M. koenikei (K. Viets, 1916): D = male from Nubui River, E = female from Akaa Falls. F – G M. stigeophora (Cook, 1966), female: F = specimen from Supon stream, G = juvenile specimen from stream upstream Sagyimase. H – I M. cf. ventriosus (K. Viets, 1916): H = male from Laboun River, I = female from Agumatsa River.

FIGURE 26 A – I. Photographs of ventral shield. A Monatractides acutiscutatus (K. Viets, 1914), female, unnamed creek upstream Sagyimase. B – C M. convexiscutata (K. Viets, 1958), stream Asukuma: B = male, C = female. D – E M. koenikei (K. Viets, 1916): D = male from Nubui River, E = female from Akaa Falls. F – G M. stigeophora (Cook, 1966), female: F = specimen from Supon stream, G = juvenile specimen from stream upstream Sagyimase. H – I M. cf. ventriosus (K. Viets, 1916): H = male from Laboun River, I = female from Agumatsa River.