Scarabaspis victoriensis, Halliday, 2010

Halliday, R. B., 2010, Revision of the Australian Eviphididae (Acari: Mesostigmata) 2596, Zootaxa 2596 (1), pp. 1-60 : 30-31

Scarabaspis victoriensis sp. nov.

( Figs 46–51 )

Material examined. Holotype. Female. Victoria, Halls Gap , 16 April 1951, H. M. Cane coll., on Onthophagus pronus, DB 681 (in ANIC) . Paratypes. Victoria. 1 female, same data as holotype except DB680 ; 1 female, Gunyah , 12 May 1963, F. Bornemissza coll., on Onthophagus mutatus, DB 479 ; 7 females, 28 miles NE of Portland , 11 November 1966, Common & Upton coll., on Onthophagus pronus, DB 685. (all in ANIC) .

Description. Female. Dorsal idiosoma ( Fig. 47 ). Dorsal shield covering entire idiosoma, length 360–468 µm, width 221–292 µm (n=5), with faint polygonal antero-lateral ornamentation, and a pair of punctate lines curving backwards from setae j 3; opisthonotal region smooth. Shield with 30 pairs of setae and ca. 14 pairs of pores; j 1 lanceolate, length 15 µm, all others short, fine, pointed; z 1 shortest, 8 µm, Z 3, Z 4 longest, 20 µm.

Ventral idiosoma ( Fig. 48 ). Tritosternum with short trapezoidal base and finely pilose laciniae. Pre-sternal area with a narrow transverse strip of lineate ornamentation. Sternal shield with irregular anterior and posterior margins, surface smooth or with very indistinct antero-lateral lineate ornamentation. Shield with three pairs of smooth pointed setae, subequal in length; and two pairs of lyrifissures; the first small, oriented at 45° to long axis of body, the second larger, transverse; third pair of sternal pores small, circular, on posterior edge of shield, one member of third pair located outside shield in a minority of specimens. Metasternal setae inserted in soft skin, flanked by narrow triangular endopodal plates between coxae III and IV. Epigynal shield with antero-lateral margins parallel, then expanding behind epigynal setae to form a bulbous posterior end; surface of shield smooth; epigynal setae inserted in soft skin clearly separate from shield. Anal shield sub-triangular, wider than long, with convex anterior and posterior margins, surface with weak polygonal ornamentation; post-anal seta slightly longer than para-anal setae; cribrum conspicuous. Unsclerotised opisthogastric skin with three pairs of setae between epigynal and anal shields, and a further six pairs lateral and posterior to anal shield; metapodal plates elongate oval, oriented obliquely. Stigmata large, located at a level between coxae III and IV, peritremes extending anterior to coxae I. Peritrematal shields wide posteriorly, narrower anteriorly, fused anteriorly and fused with dorsal shield from level of coxa II, unornamented, posterior ends irregularly truncate, with a single post-stigmatal pore, a second post-stigmatal pore on a minute platelet adjacent to posterior end of shield; exopodal plates absent.

Gnathosoma . Rostral seta h 1 and internal hypostomal seta h 3 subequal in length (ca. 22 µm), h 2 and palp coxal seta shorter (ca. 18 µm), all fine and needle-like ( Fig. 49 ). Deutosternal groove with six transverse rows of denticles, ca. 8 denticles per row; anterior row indistinct, curved; corniculi short, thick, blunt, inner margins concave; internal malae smooth, broad. 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 seta av (25 µm) much longer than pv (10 µm). Seta al on palp femur fine and needle-like; al 1 on palp genu short, thick, blunt, al 2 longer and finer. Outer edge of each palp tarsus with two long sinuous setae with rounded slightly spatulate tips, these setae distinctly diverging, not parallel; palp tarsal claw with two spatulate tines. Central process of epistome strongly serrated, long enough to reach mid-level of palp genu; basal section with sloping shoulders, margins strongly serrated ( Fig. 50 ). Fixed digit of chelicera with a large triangular distal tooth, two very small blunt proximal teeth, pilus dentilis and dorsal seta obscure, apparently minute ( Fig. 51 ); movable digit with a single large triangular distal tooth, arthrodial membrane a small rounded flap.

Legs. Chaetotaxy: Leg I. Coxa 0 0/1 0/1 0, distal seta av modified to a flat oval-shaped disc, proximal seta distinctly setiform, short and thick, with a bluntly rounded tip ( Fig. 46 ), trochanter 1 0/1 1/2 1, femur 2 3/1 2/ 2 2, genu 1 3/2 2/1 2, tibia 1 3/2 2/1 2. Leg II. Coxa 0 0/1 0/1 0, posterior seta pv modified to a flat ovalshaped disc, anterior seta av normal, pointed and needle-like, trochanter 1 0/1 0/2 1, femur 2 3/1 2/2 1, genu 2 3/1 2/1 2, tibia 2 2/1 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 2/1 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. Except for coxae I and II, all setae smooth, pointed, needle-like, 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 of this species refers to the fact that it has only been collected in the state of Victoria.

Notes. The most striking feature of S. victoriensis is the form of the proximal seta on coxa I. This seta is not a flattened oval-shaped disc as it is in other species of Scarabaspis , but takes the form of a short thick seta with a bluntly rounded tip ( Fig. 46 ). The distal seta on coxa I in S. victoriensis is always flattened and discshaped, as is the posterior ventral seta on coxa II. Scarabaspis victoriensis appears to be an uncommon species. It has only been collected on three occasions at scattered localities in southern and western Victoria, where it is phoretic on two species of dung beetles in the genus Onthophagus .

Figures

FIGURES 43–46. Scarabaspis spp., coxa I. 43, S, sternalis, female; 44, S. sternalis, female, different specimen; 45, S. sternalis, deutonymph; 46, S. victoriensis, female. Proximal seta pv arrowed. Scale bar = 50 µm.

FIGURES 47–51. Scarabaspis victoriensis, female. 47, dorsal shield; 48, ventral idiosoma; 49, hypostome; 50, epistome; 51, chelicera. Scale bar = 100 µm for 47, 48; 50 µm for 49, 50, 51.