Monatractides uniscutatus ( K. Viets, 1925 )

Pešić, Vladimir & Smit, Harry, 2014, Torrenticolid water mites (Acari: Hydrachnidia: Torrenticolidae) from Ghana, Zootaxa 3820 (1), pp. 1-80 : 74

Monatractides uniscutatus ( K. Viets, 1925)

( Figs. 50A–E , 51A–C , 52A–E )

Atractides uniscutatus K. Viets, 1925: 204 .

New records. Ghana: Ankasa Exporation Base Trail stream, upstream, Ankasa NP, 5º 16.376 N, 2º 38.655 W, alt. 94 m asl., 14.ii.2013, Smit, 1/0/0 (mounted); Ankasa Exporation Base Trail stream, Ankasa NP, 5º 16.413 N, 2º 38.810 W, alt. 81 m asl., 14.ii.2013, Smit, 0/1/0 (mounted).

Morphology. General features —Idiosoma roundish; frontal and shoulder plates fused with the large dorsal plate forming an undivided dorsal shield ( Figs. 50A , 52A–B ); frontal margin medially with large anterolaterally pointed apodemes ( Fig. 49C ); Cxgl–4 located far anteriorly, at tips of Cx-I; gnathosomal bay deep, narrow Ushaped, three pairs of knob-like protrusions at the lateral margins of gnathosomal bay; posterior suture line of Cx- IV starting almost from the centre of the posterior margin of the genital field and directed posterolaterally; excretory pore and Vgl–2 well separated from the line of primary sclerotization, Vgl–2 on the same level as excretory pore; gnathosoma elongated in lateral view, rostrum truncated ( Fig. 51C ); P-2 longer than P-4, P-3 and P- 4 distal margins with pointed tips; ventral seta on P-4 relatively long and away from distal edge ( Fig. 51B ); legs with swimming setae ( Fig. 50D ), swimming seta numbers: II-L-4, 1; II-L-4, 1; III-L-4, 1; III-L-5, 1; IV-L-3, 1; IV- L-4, 2; IV-L-5, 1. Male: medial margin of Cx-II/III moderately long; genital field subrectangular; ejaculatory complex with a small proximal chamber ( Fig. 52E ). Female: genital field large and pentagonal.

Measurements. Male —Idiosoma (ventral view: Figs. 50B , 52C ) L 655, W 534; dorsal shield ( Figs. 50A , 52A ) L 559, W 484, L/W ratio 1.16. Gnathosomal bay L 126, Cx-I total L 229, Cx-I mL 103, Cx-II+III mL 91; ratio Cx- I L/Cx-II+III mL 2.5; Cx-I mL/Cx-II+III mL 1.1. Genital field L/W 119/106, ratio 1.12; distance genital fieldexcretory pore 175, genital field-caudal idiosoma margin 216. Gnathosoma vL 134; chelicera total L 157; palp total L 164–165, dL/H, dL/H ratio: P-1, 17/21, 0.82; P-2, 48/34, 1.4; P-3, 35/28–29, 1.24; P-4, 43/21, 2.1; P-5, 21–22/ 11–12, 1.9; P-2/P-4 ratio 1.1; dL of I-L-2–6: 60, 79, 94, 89, 86; I-L-6 H 30, dL/H I-L-6 ratio 2.87; dL of IV-L- 1–6??: 84, 94, 117, 130, 136, 141.

Female —Idiosoma (ventral view: Figs. 51A , 52D ) L 706, W 594; dorsal shield ( Fig. 52B ) L 597, W 534, L/W ratio 1.12. Gnathosomal bay L 136, Cx-I total L 250, Cx-I mL 113, Cx-II+III mL 68; ratio Cx-I L/Cx-II+III mL 3.7; Cx-I mL/Cx-II+III mL 1.7. Genital field L/W 150/141, ratio 1.07; eggs maximum diameter (n = 2) 177–188; distance genital field-excretory pore 175, genital field-caudal idiosoma margin 238. Gnathosoma vL 146; chelicera total L 169; palp total L 178–180, dL/H, dL/H ratio: P-1, 18–19/23, 0.8; P-2, 50/38, 1.32; P-3, 36/32, 1.12; P-4, 48–49/23, 2.1; P-5, 26/12, 2.1; P-2/P-4 ratio 1.03; dL of I-L-2–6: 66, 80, 103, 94, 87; I-L-6 H 33–34, dL/H I-L-6 ratio 2.6; dL of IV-L: 95, 108, 114, 146, 148, 115.

Remarks. The specimens from Ghana agree well in general morphology with Monatractides uniscutatus . This species was described by K. Viets (1925) based on a single male collected in the stream Ngong in Cameroon. No further record of this species was published after the original description and we give the first description of the female. Monatractides maryellenae ( Cook, 1966) , described from several sites in Liberia closely resembles M. uniscutatus , but differs in larger dimensions and in proportional lenghts of the palp segments (see Cook 1966). Distribution. Cameroon ( K. Viets 1925), Ghana (first record).

Figures

FIGURE 50 A – E. Monatractides uniscutatus (K. Viets, 1925), male, Ankasa Exporation Base Trail stream: A = dorsal shield; B = idiosoma, ventral view; C = frontal margin of idiosoma, dorsal view; D = IV-L; E = I-L- 5 and - 6. Scale bars = 100 Μm.

FIGURE 51 A – C. Monatractides uniscutatus (K. Viets, 1925, female, Ankasa Exporation Base Trail stream: A = idiosoma, ventral view; B = palp, lateral view; C = gnathosoma. Scale bars = 100 Μm.

FIGURE 52 A – E. Photographs of Monatractides uniscutatus (K. Viets, 1925) (A, C, E = male, B, D = female), Ankasa Exporation Base Trail stream: A – B = dorsal shield; C – D = idiosoma, ventral view; E = ejaculatory complex.

FIGURE 49 A – E. Photographs of: A – B Monatractides sp. 1, male, Apkonu stream: A = dorsal shield; B = idiosoma, ventral view. C – E Monatractides sp. 2, male, Kintampo Falls: C = dorsal shield; D = idiosoma, ventral view; E = inner side of genital field (arrow showing ejaculatory complex reduced to sclerotized framework).