Scarabaspis masani, Halliday, 2010

Halliday, R. B., 2010, Revision of the Australian Eviphididae (Acari: Mesostigmata) 2596, Zootaxa 2596 (1), pp. 1-60 : 18-21

Scarabaspis masani sp. nov.

( Figs 18–26 )

Material examined. Holotype. Female. New South Wales, Coolendel, 30 km west of Nowra , 10 March 1996, M. Morris coll., on Onthophagus leai in wombat dung (in ANIC) . Paratypes. New South Wales. 7 females, 6 males, same data as holotype ; 1 female, Marulan , 23 April 1964, G. F. Bornemissza coll., on Onthophagus nurubuan, DB 522 . Victoria. 2 females, 1 male, 9 miles south of Yanakie , 3 May 1963, G. F. Bornemissza coll., on Onthophagus mniszechi, DB 380, DB381, DB382 ; 1 female, Wannon Recreation Reserve , 26 September 1947, B. B. Giben and P. B. Carne coll., on Onthophagus posticus, DB 679. (all in ANIC) .

Description. Female. Dorsal idiosoma ( Fig. 18 ). Dorsal shield covering entire idiosoma, length 413–452 µm, width 263–245 µm (n=8), with faint polygonal ornamentation throughout, weakest medially, some stronger posterior and postero-lateral lines of ornamentation. Shield with 30 pairs of setae and ca. 14 pairs of pores; j 1 lanceolate, length 15 µm, all others fine and pointed; z 1 shortest, 8 µm, Z3, Z4 longest, 20 µm.

Ventral idiosoma ( Fig. 19 ). Tritosternum with short trapezoidal base and finely pilose laciniae. Pre-sternal area with faint transverse 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 anterior pair oriented at 30° to long axis of body, posterior pair transverse. Third pair of pores inconspicuous, variably inserted in soft skin posterior to sternal shield or on extreme posterior edge of shield; metasternal setae free in soft skin, flanked by narrow triangular endopodal plates between coxae III and IV. Free exopodal plates absent, apparently fused with peritrematal shield. Epigynal shield with antero-lateral margins parallel or slightly narrowing posteriorly, then expanding sharply 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 postero-lateral margins, anterior margin with two small rounded protrusions; surface with 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 four pairs lateral to anal shield; metapodal plates elongate oval, oriented obliquely. Stigmata located at a level between coxae III and IV, peritremes extending anterior to coxae I. Peritrematal shields wide medial to peritremes, narrower outside peritremes, fused with dorsal shield from level of coxa II, unornamented, extending behind stigmata to mid-level of coxa IV; posterior end of shield irregularly rounded, with two small pores behind stigma.

Gnathosoma . Rostral seta h 1 and hypostomal seta h 3 subequal in length (ca. 27 µm), h 2 and palp coxal seta shorter (ca. 18 µm), all fine and needle-like ( Fig. 20 ). Deutosternal groove with five transverse rows of denticles, 6–8 denticles per row, and a smooth anterior transverse line; corniculi robust, slightly curved inward; internal malae strongly 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 seta av long (ca. 35 µm), pv much shorter (ca. 15 µm). Seta al on palp femur long and slightly spatulate, al 1 on palp genu short and blunt, al 2 short and pointed. Outer edge of each palp tarsus with two long parallel sinuous setae with rounded tips (macroeupathidia); palp tarsal claw with two spatulate tines. Central process of epistome strongly spiculate, long enough to reach mid-level of palp genu; basal section with square shoulders, anterior margin strongly serrated ( Fig. 21 ). Fixed digit of chelicera with a small distal tooth, a large medial tooth, and a small proximal tooth, pilus dentilis short, fine, dorsal seta fine, prostrate ( Fig. 22 ); movable digit with a prominent terminal hook, a large triangular tooth, and a low proximal ridge, arthrodial membrane a small rounded flap.

Legs. Chaetotaxy: Leg I. Coxa 0 0/1 0/1 0, trochanter 1 0/1 1/2 1, femur 2 3/2 2/2 2, genu 1 3/2 2/1 2, tibia 1 3/2 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 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. All setae smooth and pointed, most dorsal setae thicker than ventral and lateral setae; setae on coxae I and II unmodified, setiform. 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. Insemination ducts unfused, opening into sacculus through circular pores ( Fig. 23 ), sacculus not visible in available specimens, apparently unsclerotised.

Male. Dorsal idiosoma. Dorsal shield length 376–389 µm, width 234–242 µm (n=6), structure and chaetotaxy as for female.

Ventral idiosoma ( Fig. 24 ). Pre-sternal area with a pair of irregular obliquely oriented elongate platelets. Sternal, metasternal, and epigynal shields fused to form a sterno-genital shield, with five pairs of smooth setae and two pairs of lyrifissures; anterior pair oblique; second pair transverse; third pair of pores minute, circular. Antero-lateral and postero-lateral corners of shield bluntly pointed, surface of shield smooth, metapodal plates very small, indistinct, other features of ventral idiosoma as for female.

Gnathosoma . Fixed digit of chelicera with a blunt distal tooth and a large proximal tooth; pilus dentilis and dorsal seta obscure; movable digit with a single very robust tooth; spermatodactyl robust, projecting beyond end of movable digit, widened distally ( Fig. 25 ). Other features of gnathosoma as for female.

Legs. Legs II slightly thicker than those of female, seta av on femur II modified to a thick rounded spur ( Fig. 26 ); legs otherwise as for female.

Etymology. This species is named in honour of Peter Mašán of Bratislava, who has made many valuable contributions to the systematics of Eviphididae , including the present study.

Notes. Scarabaspis masani lacks the modified oval disc-like setae on coxae I and II that are usually considered as diagnostic for the genus. Instead, these setae are normal, pointed and needle-like. This makes S. masani appear superficially similar to a species of Alliphis . However, S. masani has several important character states that are typical for Scarabaspis and are absent or rare in Alliphis : (1) epigynal setae of female in soft skin, not on epigynal shield; (2) metasternal platelets absent, metasternal setae and pores inserted in soft skin; (3) macroeupathidia present on palp tarsus; (4) free expodal plates I–II absent; (5) antero-ventral seta on femur II of male expanded and spur-like; (6) ventral spurs absent from leg IV of male. For these reasons I have placed this species in Scarabaspis rather than Alliphis . It should also be noted that another new species described below, S. victoriensis , has only one of the setae on coxa I modified, and the other normal (see below, and Discussion). Scarabaspis masani is known from four localities in Victoria and southern New South Wales, where it is phoretic on dung beetles in the genus Onthophagus . Both male and female mites are phoretic.

Figures

FIGURES 18–23. Scarabaspis masani, female. 18, dorsal shield; 19, ventral idiosoma; 20, hypostome; 21, epistome; 22, chelicera; 23, insemination ducts. Scale bar = 100 µm for 18, 19; 50 µm for 20, 21, 22; 25 µm for 23.

FIGURES 24–29. Scarabaspis spp., males. 24, S. masani, ventral idiosoma; 25, S. masani, chelicera; 26, S. masani, femur and genu II; 27, S. sternalis, ventral idiosoma; 28, S. sternalis, chelicera; 29, S. sternalis, femur and genu II. Scale bar = 100 µm for 24, 27; 50 µm for 25, 26, 28, 29.