Monatractides thalia, Pešić, Vladimir & Smit, Harry, 2014

Pešić, Vladimir & Smit, Harry, 2014, Torrenticolid water mites (Acari: Hydrachnidia: Torrenticolidae) from Ghana, Zootaxa 3820 (1), pp. 1-80 : 49-51

Monatractides thalia n. sp.

( Figs. 32A–C , 33A–F , 37G , 38G )

Type series. Holotype male, dissected and slide mounted, Ghana, Agumatsa River at first bridge, Agumatsa Wildlife Sanctuary, 7º 06.830 N, 0º 35.760 E, alt. 253 m asl., 22.ii.2013, Smit. Paratypes: 2/0/0, Kue River, Kyabobo NP, 8º 31.087 N, 0º 36.049 E, alt. 208 m asl., 25.ii.2013, Smit, 1/0/0 dissected and slide mounted.

Diagnosis (Female unknown). Ventral margin of P-2 and P-3 each with stout, sharp-pointed seta; P-4 laterally with one or two short peg-like setae located distally from the ventral tubercle bearing relatively long setae; gnathosoma with a stout and truncated rostrum.

Description. Male. General features —Idiosoma elongated; frontal platelets almost equal in size with shoulder platelets; frontal margin medially pointed, between anterolaterally orientated apodemes ( Fig. 32A ); Cxgl-4 located far anteriorly, near tip of Cx-I; gnathosomal bay deep U-shaped, proximally wide box-shaped; medial margin of Cx-II/III relatively short; posterior suture line of Cx-IV originating from lateral edge of genital field and strongly extending posteriorly beyond posterior margin of genital field; genital field subrectangular; excretory pore on the same level as Vgl–2 and away from the line of primary sclerotization; gnathosoma with stout, sharply bend and truncated rostrum ( Figs. 33E–F ); palp compact, P-2 equal in length to P-4, P-2 proximally with sharp bend, distally extended, ventrodistal protrusion bearing stout, sharp-pointed seta, ventral margin of P-3 with stout, sharp-pointed seta, P-4 basally enlarged, laterally with one or two short peg-like setae located distally to the ventral tubercle bearing relatively long setae ( Figs. 33A–C ); I-L with I-L-6 L/H ratio 2.0–2.1, dorsal margin strongly convex ( Fig. 33D ).

Measurements (holotype, in parentheses paratype)—Idiosoma (ventral view: Figs. 32C , 38G ) L 594 (613), W 373 (392); dorsal shield ( Figs. 32B , 37G ) L 484 (503), W 334 (353), L/W ratio 1.45 (1.43); dorsal plate L 450 (464); shoulder platelets L 116–122 (119), W 53 (53–56), L/W ratio 2.2–2.3 (2.1–2.24); frontal platelets L 116 (119–120), W 47 (50), L/W ratio 2.5 (2.4); shoulder/frontal platelets L ratio 1.0–1.05 (0.99–1.0). Gnathosomal bay L 138 (150), Cx-I total L 256 (256), Cx-I mL 128 (106), Cx-II+III mL 25 (45); ratio Cx-I L/Cx-II+III mL 10.2 (5.7); Cx-I mL/Cx-II+III mL 5.1 (2.4). Genital field L/W 97 (102–103)/77–78 (81), ratio 1.25 (1.26); distance genital field-excretory pore 167 (156), genital field-caudal idiosoma margin 208 (208). Gnathosoma vL 151 (176); chelicera total L 175 (192); palp total L 221–223, dL/H, dL/H ratio: P-1, 25/39, 0.63 (25/39, 0.63); P-2, 78–79/65, 1.22 (88/68, 1.3); P-3, 43/48, 0.9 (46/50, 0.9); P-4, 54/31, 1.75 (61–62/34, 1.8); P-5, 21–22/12, 1.75 (23/13, 1.8); P- 2/P-4 ratio 1.45 (1.43); dL of I-L-2–6: 57, 70 (73), 83 (83), 79 (86), 84 (87); I-L-6 H 41–42 (41–42), dL/H I-L-6 ratio 2.0 (2.1).

Female: unknown.

Etymology. The species is named after Thalia (Ancient Greek: Θάλεια), one of nine Muses from Greek mythology, who was a patron of comedy. The species name is a noun in apposition (in the nominative case).

Discussion. The new species is rather similar to M. opimipalpis ( K.O. Viets, 1974) , a species known from a single female from Congo ( K.O. Viets & Böttger 1974), with respect to the shape of the coxal field and palps (ventral margin of P-2 and -3 with stout, sharp-pointed seta, P-4 with a short peg like seta located near the ventral tubercle). The latter species can be distinguished in a gnathosoma with apically more slender and less truncated rostrum (see: K.O. Viets & Böttger 1974, Fig. 73).

Monatractides (Monatractides) pinguipalpis ( Cook, 1966) ( Liberia) , similar in presence of stout, sharp-poined setae on the ventral margin of P-2 and P-3, can be easily separated by a differently shaped P-4 (the lateral peg-like setae not illustrated in the original description, ventral margin with two long setae near proximal end and a short, peg-like seta near distal end), a comparatively longer and narrower P-5, a less stout I-L-6 and gnathosoma with apically more pointed, not truncated, rostrum ( Cook 1966).

Remarks. In males of the present study the ejaculatory complex was not found, but sclerotized framework immediately above the genital field can be hardly visible.

Habitat. A sandy/bouldary streams, shaded by riparian vegetation ( Fig. 53C and Fig. 45 C in Pešić et al. 2013). Distribution. Ghana.

Figures

FIGURE 45. Distribution map of some selected Monatractides species (species number corresponds with numbers in Map): 1 — M. microstoma Koenike, 1898, 2 — M. amplipalpis Lundblad, 1951, 3 — M. longicoxalis Cook, 1966, 4 — M. dolichosoma Cook, 1966, 5 — M. congoensis K. O. Viets, 1974, 6 — M. rivalis K. O. Viets, 1974, 7 — M. procursa K. O. Viets, 1974, 8 — M. nigromontanus Goldschmidt & Smit, 2009; populations of Monatractides microstoma species-complex from Ghana are marked by X.

FIGURE 32 A – C. Monatractides thalia n. sp., male, Agumatsa River: A = frontal margin of idiosoma, dorsal view; B = dorsal shield; C = idiosoma, ventral view. Scale bar = 100 Μm.

FIGURE 33 A – F. Monatractides thalia n. sp., male (A – B, D – E—from Agumatsa River, C, F—from Kue River): A, C = palp, medial view; B = palp, lateral view; D = I-L- 5 and - 6; E-F = gnathosoma. Scale bars = 100 Μm.

FIGURE 37 A – I. Photographs of dorsal shield. A – B Monatractides melpomene n. sp., Amedzofe Falls: A = male holotype, B = female paratype. C – D M. euterpe n. sp., creek upstream Sagyimase: C = male holotype, D = female paratype. E – F M. polyhymnia n. sp., Kue River: E = male holotype, F = female paratype. G M. thalia n. sp., male holotype, Agumatsa River. H M. terpsichore n. sp., female holotype, Plunge pool. I M. urania n. sp., male paratype, Kintampo Falls.

FIGURE 38 A – I. Photographs of ventral shield. A – B Monatractides melpomene n. sp., Amedzofe Falls: A = male holotype, B = female paratype. C – D M. euterpe n. sp., creek upstream Sagyimase: C = male holotype, D = female paratype. E – F M. polyhymnia n. sp., Kue River: E = male holotype, F = female paratype. G M. thalia n. sp., male holotype, Agumatsa River. H M. terpsichore n. sp., female holotype, Plunge pool. I M. urania n. sp., male paratype, Kintampo Falls.

FIGURE 53 A – E. Photographs of selected sampling sites: A—Laboun River (sampling site of Torrenticola motasi, T. harrisoni, Monatractides acutiscutatus, M. cf. ventriosa, M. microstoma - species complex), B—Apkonu stream (sampling site of Torrenticola anomallela, T. harrisoni, Monatractides stigeophora, M. microstoma - species complex). C—Agumatsa River at first bridge (type locality of Monatractides thalia n. sp. and sampling site of Torrenticola harrisoni, Monatractides cf. ventriosus). D—Tagbo River, downstream of falls (sampling site of Torrenticola harrisoni, T. motasi, T. bomiensis, Monatractides microstoma - species complex). E—Tagbo River, downstream (sampling site of Torrenticola harrisoni). Photos. H. Smit.