Hexaxonopsis (Hexaxonopsis) subtruncata, Smit, Harry, 2016

Smit, Harry, 2016, The water mite family Aturidae Thor (Acari: Hydrachnidia) from Ghana, with the description of twelve new species, Zootaxa 4158 (4), pp. 523-543 : 535-537

Hexaxonopsis (Hexaxonopsis) subtruncata n. sp.

( Figs. 9A–D )

Material examined. Holotype male, Unnamed stream crossing road to Ankasa NP, Ghana, 5 11.435 N 2 39.429 W.

alt. 20 m a.s.l., 27-ii-2011. Paratypes: one male, Fuller Falls , Ghana, 8 0 4.975 N 1 47.842 W, alt . 189 m a.s.l., 6-iii- 2011; two females, Akaa Falls , Ghana, 6 10.516 N 0 11.723 W, alt . 180 m a.s.l., 9-iii-2011; two males, three females, Ankasa River , Ankasa NP, Ghana, 5 13.011 N 2 39.126 W, alt . 60 m a.s.l., 13-ii-2013; 22 males, seven females, Amedzofe Falls , 6 50.656 N 0 26.868 E, alt . 599 m a.s.l., 20-ii-2013; one male, Laboun River downstream of falls, Ghana, 8 19.836 N 0 35.487 E, alt . 342 m a.s.l., 24-ii-2013.

Diagnosis. Dorsal shield with a short truncated extension; excretory pore fused with dorsal shield, flanked by a pair of glandularia; between fourth leg sockets and genital field two pair of glandularia, most posterior pair close to genital field in male and both glandularia more or less halfway in female.

Description. Both sexes: Colour pale yellow. Dorsal shield fused anteriorly with ventral shield; with six pairs of glandularia, two pairs close to each other, most posterior pair flanking the excretory pore, posteriorly with a short truncate extension. Anterior part of coxal field bluish, but in a number of paratypes coxal field without bluish colour; a number of paratypes with a transverse rose-colour band. Cx-I and Cx-II with a hook-like extension. Genital field with three pairs of acetabula; P4 ventrally expanded, with a stout seta. Number of swimming setae: III-leg-4 with two, III-leg-5 with four, IV-leg-4 with two and IV-leg-5 with three. Male: Idiosoma dorsally 389 (381–429) long and 316 (336–356) wide, ventrally 381 (373–412) long. Dorsal shield 292 (308–332) wide. Between fourth leg sockets and genital field two pairs of glandularia, one pair halfway and one pair close to genital field. Gonopore 35 long. Length of P1–5: 30, 41, 34, 72, 24. Length of I-leg-4–6: 52, 70, 70. Length of IV-leg-4–6: 64, 82, 70. IV-leg not modified, IV-leg-5 ventrally with seven setae of different length, IV-leg-6 ventrally with five short setae of equal length.

Female: Idiosoma dorsally 382 (390–437) long and 328 (316–381) wide, ventrally 375 (389–421) long. Dorsal shield 296 (284–356) wide. Halfway between fourth leg sockets and genital field two pairs of glandularia. Gonopore 46 long and 74 wide. Length of P1–5: 28, 34, 30, 66, 24;. Length of I-leg-4–6: 44, 60, 58. Length of IVleg-4–6: 66, 74, 64.

Etymology. Named for the short truncate extension of the dorsal shield.

Remarks. Most male Hexaxonopsis species have the two pairs of glandularia between the fourth leg sockets and the genital field either close to each other, or the posterior pair is distanced from the genital field. Only Hexaxonopsis marshallae ( Cook, 1966) from Liberia has a pair of glandularia close to the genital field, but the idiosoma is more tapering posteriorly and the pair of glandularia flanking the excretory pore is absent. Female H. kimalis ( Cook, 1966) from Liberia have a similar configuration of the dorsal and ventral glandularia, but lack the short truncate extension of the dorsal shield.

There is some variation in the position of the glandularia between the fourth leg sockets and the genital field. Females from Amedzofe Falls have these glandularia more distanced from each other, while in the males the more posterior pair is more distanced from the genital field. Moreover, these specimens lack the bluish colour of the coxal field, but the bluish colour is lacking in some other specimens as well. These differences are not large enough to warrant the description of another new species.

Figures

FIGURE 9 A – D. Hexaxonopsis subtruncata n. sp., A – C - holotype male, D = paratype female. A = dorsum; B = venter; C = palp; D = venter. Scale bars = 50 µm.