Evimirus pentagonius Karg, 1996

Halliday, R. B., 2010, Revision of the Australian Eviphididae (Acari: Mesostigmata) 2596, Zootaxa 2596 (1), pp. 1-60 : 13-14

Evimirus pentagonius Karg

( Figs 11, 12 )

Evimirus pentagonius Karg, 1996: 150 .

Male. Dorsal idiosoma ( Fig. 11 ). Dorsal shield length 292 µm, width 250 µm, with 30 pairs of setae and ca. 15 pairs of pores; setae j 1 and z 1 very minute, longest setae J 5, Z 5 ca. 10 µm; four pairs of pores between J and Z setae very large and conspicuous.

Ventral idiosoma ( Fig. 12 ). Tritosternum inserted on a narrow transverse basal sclerite, base rectangular, laciniae short, finely pilose. Pre-sternal plates large, trapezoidal, each with an irregular transverse groove. Sternal, metasternal, endopodal and epigynal shields fused to form a sterno-genital shield with five pairs of setae and three pairs of lyrifissures; setae decreasing in length from st 1 to st 5; first pair of lyrifissures stp 1 transverse, second pair stp 2 very large, transverse, third pair smaller, longitudinal; surface of shield with irregular lines of ornamentation. Genital pores in soft skin adjacent to posterior end of shield, posterior end of sterno-genital shield partly overlaying a small oval post-genital plate. Opisthogastric plates behind coxae IV very large, triangular, their medial edges almost abutting, each with a pore on its anterior margin. Anal shield large, trapezoidal, smooth; anus in posterior half of shield, post-anal seta longer than para-anal setae. Peritrematal shields very wide, beginning anterior to coxae I, posterior end extending well beyond coxae IV, almost abutting anal shield. Shield with a pore at anterior level of coxae II and a large post-stigmatal pore behind level of coxae IV, outline of metapodal plates visible behind post-stigmatal pores. Peritremes on inner edges of peritrematal shields, sharply elbowed at anterior level of coxa II, stigmata at anterior level of coxa IV, a small post-stigmatal pore on inner edge of shield at mid-level of coxa IV. Three pairs of exopodal plate present, first triangular, between coxae I and II, second elongate and narrow, adjacent to coxa III, third narrow, embracing coxa IV. Opisthogastric skin with three pairs of robust setae between anal and peritrematal shields, three pairs lateral to anal shield, and two longer robust pairs on poster-lateral margin.

Material examined. New Caledonia. Holotype and 18 paratypes, Hienghen and Ile des Pins, ZMB45778-45779 (in ZMB). Australia, Northern Territory. 10 females, Darwin , Coconut Grove , 14 November 1972, T. Angeles, ANIC445 (7 in ethanol, 3 on slides, in ANIC); 5 females, 1 male, same data except ANIC444 (4 females in ethanol, 1 female, 1 male on slides, in ANIC).

Notes. Karg (1996) described this species from New Caledonia, and it is now recorded for the second time. The female of this species is distinctive in having a large triangular plate and two small platelets behind coxa IV on each side, the postero-median corners of the peritrematal shields pointed rather than broadly rounded as they are in other species, and a distinctly convex posterior margin of the epigynal shield. In the specimens from both New Caledonia and Australia, the pre-sternal plates are rectangular to trapezoidal, rather than oval as illustrated by Karg, and bear one or two transverse lines; there are 3–4 small circular nodules on the posterior margin of the epigynal shield; and there is a pair of large oval-shaped markings in the posterior ends of the peritrematal shields, apparently corresponding to the metapodal plates, which are fully absorbed into the peritrematal shields. Lindquist et al. (2009) illustrated the female of Evimirus sp. from Queensland, which appears to be a specimen of E. pentagonius (their Fig. 12.45F ). In the male of E. pentagonius , the plates behind coxae IV are very large and triangular, with median edges that almost meet behind the posterior end of the sterno-genital shield ( Fig. 12 ). Karg (1989) showed a single large ventral shield in this area in the male of E. uropodinus , suggesting that the males of other species of Evimirus could be a valuable extra source of taxonomic information.

Figures

FIGURES 9–12. Evimirus spp. 9, Evimirus sp., female, ventral aspect, showing coiled strands of material extruded from post-stigmatal pores, scanning electron micrograph; 10, Evimirus sp., female, lateral habitus, scanning electron micrograph (photos by D.E. Walter and C. Meacham); 11, E. pentagonius, male, dorsal shield; 12, E. pentagonius, male, ventral idiosoma. Scale bar = 100 µm.