Evimirus scutellatus, Halliday, 2010

Halliday, R. B., 2010, Revision of the Australian Eviphididae (Acari: Mesostigmata) 2596, Zootaxa 2596 (1), pp. 1-60 : 15-16

Evimirus scutellatus sp. nov.

( Figs 13–17 )

Material examined. Holotype. Female : Australia, Queensland, 1.6 km SW of Yungaburra, 17°18'S 145°35'E, 17 February 1973, rainforest, alt 720 m, R. W. Taylor coll., ANIC440 (in ethanol, in ANIC) . Paratypes. Queensland. 23 females, same data as holotype ; 1 female, Cape Tribulation, Oliver Creek , 16°08'30"S 145°26'30"E, 27 June 1995, rainforest, ground litter # 4, F. Beaulieu, UQIC Reg. # 83613 (on slide, in UQIC) ; 1 female, Wongabel State Forest , 13–16 April 1994, soil # 13 (w13), C. Thebaud, UQIC Reg. # 83614 (on slide, in UQIC) ; 1 female, Atherton, Robson Creek , 17°07'S 145°37'E, 16 January 1996, leaf litter ( R. Kitching L 5), D. E. Walter, UQIC Reg. # 83731 (on slide, in UQIC) ; 10 females, Gillies Highway, 2 km east of Mount Nomico , 17°13'S 145°42'E, 28 October 1976, alt 720 m, R . W. Taylor and T. A. Weir coll. , rainforest, ANIC539 (in ethanol, in ANIC) ; 2 females, McNamee Creek , 17°40'S 145°49'E, 8 July 1971, R . W. Taylor and J. Feehan , alt 300m, rainforest, ANIC364 (in ethanol, in ANIC) ; 12 females, Eacham National Park , 17°18'S 145°37'E, 1–7 Oct 1972, rainforest, alt 760 m, R. W. Taylor coll., ANIC431 (in ethanol, in ANIC) ; 1 female, Eacham National Park , 17°18'S 145°37'E, 1–7 October 1972, rainforest, alt 760 m, R. W. Taylor coll., ANIC434 (in ethanol, in ANIC) ; 7 females, Barrine National Park , 17°16'S 145°38'E, 22 February 1973, rainforest, alt 760 m, R. W. Taylor coll., ANIC438 (2 on slides, 5 in ethanol, in ANIC) ; 6 females, Barrine National Park , 17°16'S 145°38'E, 21 February 1973, rainforest, alt 760 m, R. W. Taylor coll., ANIC439 (5 in ethanol, 1 on slide, in ANIC) ; 11 females, Barrine National Park , 17°16'S 145°38'E, 21 March 1975, rainforest, alt 760 m, R. W. Taylor coll., ANIC485 (in ethanol, in ANIC) ; 4 females, Barrine National Park , 17°16'S 145°38'E, 21 March 1975, rainforest, alt 760 m, R. W. Taylor coll., ANIC486 (in ethanol, in ANIC) ; 1 female, Wongabel State Forest , 19–20 May 1980, I. D. Naumann and J. Cardale, rainforest, ANIC678 (on slide, in ANIC) ; 1 female, Lake Eacham National Park , 25 May 1980, I. D. Naumann and J. C. Cardale, rainforest, ANIC681 (on slide, in ANIC) . Northern Territory. 1 female, Darwin, Coconut Grove , 12°27'S 130°50'E, 14 November 1972, T. Angeles coll., ANIC445 (in ethanol, in ANIC) ; 1 female, Baroalba Spring , 12°47'S 132°51'E, 20 November 1972, rainforest, R. W. Taylor coll., ANIC470 (in ethanol, in ANIC).

Description. Female. Dorsal idiosoma ( Fig. 13 ). Idiosoma highly arched, almost hemispherical, length 358–389 µm, width 287–318 µm, height ca. 155 µm (n=5), colour pink. Dorsal shield covering entire dorsum, surface smooth, with 30 pairs of fine pointed setae (18 podonotal, 12 opisthonotal) and ca. 15 pairs of pores; setae increasing in length from minute, j 1 and z 1, ca. 5 µm, to longest, J 5 and Z 5, ca. 15 µm; lateral and posterior pores very large and conspicuous, oval shaped.

Ventral idiosoma ( Fig. 14 ). Tritosternum with short base and short, very fine, sparsely pilose laciniae. Presternal area with a pair of large pentagonal pre-sternal plates, their medial edges adjacent, each with a transverse line of ornamentation. Sternal shield laterally compressed, width at narrowest point 25 µm, length along mid-line 80 µm; with very long pointed arms between coxae I–II and II–III; anterior margin concave, posterior margin convex, rounded; shield with three pairs of minute pointed setae and two pairs of lyrifissures, anterior pair small, transverse, posterior pair very large, transverse; surface of shield with two ∩-shaped anterior markings. Metasternal plates large, elongate, extending posteriorly to mid-level of coxae IV, with a pair of minute metasternal setae near their anterior end, and a pair of pores on the inner margin. Endopodal plates between coxae III and IV large, triangular, with concave margins, closely abutting metasternal plates. Epigynal shield with a very narrow elongate anterior section, widening behind coxae IV to an oval-shaped posterior section, width at widest point 60 µm; surface of shield smooth except for a pair of faint longitudinal lines parallel to edges of shield, and 3–4 small nodules on posterior margin; with a pair of minute pointed epigynal setae; epigynal pores located off shield; a pair of small oval accessory plates partly underlying edges of epigynal shield at posterior level of coxae IV. Anal shield subtriangular, with convex anterior margin and concave lateral margins; width 80 µm, length 70 µm; anus located in posterior half of shield; para-anal and post-anal setae subequal in length (ca. 20 µm); surface of shield smooth, with a pair of large pores located in lateral corners; cribrum conspicuous. Peritrematal shields very wide, widest behind coxae IV; with a pair of large poststigmatal pores; surface smooth, completely incorporating metapodal plates; fused with dorsal shield anteriorly, a narrow strip of dorsal shield sometimes encroaching slightly onto ventral idiosoma. Stigmata at a level between coxae III and IV; peritremes sinuous, extending to anterior level of coxae I, sharply elbowed between coxae I and II. Exopodal plate II–III trapezoidal, anterior margin straight, posterior margin narrower, notched to accommodate anterior end of triangular exopodal plate III–IV. Opisthogastric skin with two pairs of very small circular platelets behind coxae IV, a pair of short setae adjacent to posterior margin of epigynal shield, and eight pairs of robust setae.

Gnathosoma . Rostral setae h 1 very long and fine, ca. 80 µm, internal setae h 3 shorter, ca. 50 µm, external setae h 2 and palp coxal setae shorter, subequal, ca. 30 µm ( Fig. 15 ). Deutosternal groove with five wide transverse rows of denticles, about 7–8 irregular teeth per row, third row curved, and a smooth curved anterior line; margins of groove very indistinct. Corniculi robust, curved slightly inward, internal malae finely fringed. Palp chaetotaxy: trochanter 0 0/1 0/1 0, femur 1 1/0 2/0 1, genu 2 1/0 2/0 1, tibia 14, tarsus 15. Palp trochanter setae av and pv long and fine, ca. 50 µm. Seta al on palp femur thick, spine-like; al 1 and al 2 on palp genu thick, spine-like, with spatulate tips. Palp tarsal claw with two large spatulate tines and a much smaller third basal tine, and a pair of blunt-tipped sinuous parallel terminal setae. Epistome with a single elongate central projection, its lateral and basal margins strongly serrated ( Fig. 16 ). Fixed digit of chelicera with a low medial ridge, a small triangular tooth, and a larger triangular distal tooth; pilus dentilis minute, dorsal seta not visible ( Fig. 17 ). Movable digit with a low blunt medial tooth and a triangular distal tooth, arthrodial membrane a small rounded flap.

Legs. Chaetotaxy: Leg I. Coxa 0 0/1 0/1 0, trochanter 1 0/1 0/2 1, femur 2 3/1 2/2 2, genu 1 3/1 2/1 2, tibia 1 2/1 2/1 2. Leg II. Coxa 0/1 0/1 0, trochanter 1 0/1 0/2 1, femur 2 3/1 2/2 1, genu 1 3/1 2/0 2, tibia 1 1/1 2/1 2, tarsus 3 3/2 3/2 3 + mv, md. Leg III. Coxa 0 0/1 0/1 0, trochanter 1 0/1 0/2 1, femur 1 2/1 1/0 1, genu 1 2/1 2/0 1, tibia 1 1/1 2/1 1, tarsus 3 3/2 3/2 3 + mv, md. Leg IV. Coxa 0 0/0 0/1 0, trochanter 1 0/1 0/2 1, femur 1 2/1 1/ 0 1, genu 1 2/1 2/0 1, tibia 1 1/1 2/1 1, tarsus 3 3/2 3/2 3 + mv, md. All setae smooth and pointed, most dorsal setae thicker than ventral and lateral setae. Tarsi I–IV each with a well-developed pair of claws and a rounded pulvillus, claws on tarsus I smaller and less robust than those on tarsi II–IV.

Genital structures. Not visible in available specimens.

Etymology. The name scutellatus (small plate) refers to the small size of the two pairs of platelets in the soft skin posterior to coxae IV in this species.

Notes. Evimirus scutellatus may be distinguished from E. leptogenitalis , E. breviscuti and E. uropodinus by the fact that the distance between the postero-median corners of the peritrematal shields is smaller than the width of the anal shield; from E. pulcherpori , E. convergens , and E. pentagonius by the fact that it lacks large sclerotised plates posterior to coxa IV, and from E. kargi by the fact that it has large conspicuous pores in the peritrematal shields posterior to the stigmata. It appears to be most similar to E. kargi from New Guinea, but clearly differs in the very small size of the two pairs of platelets posterior to coxa IV and the presence of large post-stigmatal pores. The dorsal shield setae of most species are very short and fine. The number of pairs of setae in published illustrations varies from 22 to 29, and Evans & Till (1979) reported setae j 1 and z 1 as apparently absent. Evimirus scutellatus has a full complement of 30 pairs of setae, but j 1 and z 1 are extremely minute and barely visible even under high magnification. The specimens examined here include 84 females and zero males. This suggests, but does not prove, that the species may be thelytokous.

Figures

FIGURES 13–17. Evimirus scutellatus, female. 13, dorsal shield; 14, ventral idiosoma; 15, hypostome; 16, epistome; 17, chelicera. Scale bar = 100 µm for 13, 14; 50 µm for 15, 16, 17.