Scapheremaeus tuberculosus, Colloff, Matthew J., 2010

Colloff, Matthew J., 2010, The hyperdiverse oribatid mite genus Scapheremaeus (Acari: Oribatida: Cymbaeremaeidae) in Australia, with descriptions of new species and consideration of biogeographical affinities, Zootaxa 2475, pp. 1-38 : 26-28

Scapheremaeus tuberculosus sp. nov.

( Figs. 4 , 13 )

Dimensions. Holotype female: length 596, breadth 358; paratype females: lengths 631, 656, 636; breadths 383, 359, 385; paratype males: lengths 570, 581; breadths 338, 343. Ratio of length of prodorsum to total length (holotype): 0.24.

Prodorsum. With pattern of irregular ridges laterally medially ( Fig. 13 a). Rostrum broad, blunt, Ushaped. Rostral seta (ro) smooth, curved ventromedially, ca. 28 long. Lateral carinae absent. Lamellar seta covered with dark, club-shaped cerotegument, on elongated lamellar apophysis emerging from translamellar ridge. Costulae straight, converging apically, extending posteriorly as far as bothridia. Interbothridial ridge faint, weakly-developed. Interlamellar seta absent. Sensillus with large, smooth, club-shaped, darklypigmented head, ca. 41 long, 22 broad, emerging on short stalk from bothridium (diameter 16) positioned adjacent to dorsosejugal suture. Region posterior of interbothridial ridge with irregular plaques and ridges.

Notogaster. Length 451. Circumdorsal scissure entire, oval ( Fig. 13 a); with diagonal extensions into humeral region. Lenticulus wedge-shaped, ovoid (37 long, 22 broad) with discrete margins. With a shallow depression on either side of lenticulus, demarcated by staple-shaped ridges on dorsal circumnotogastral plate. Humeral process a well-developed acute spine in dorsal view. Dorsal circumnotogastral plate plicate, tuberculate. Centrodorsal plate 348 long, 222 broad, oval, broadest at level midway between setae lm and lp, with centrodorsal ridge extending as far as opening of gla, but lacking posteriolateral concavities. Centrodorsal microsculpture consisting of large ovoid tubercles, particularly evident near centrodorsal margin. With ten pairs of short notogastral setae, similar in size and shape, covered in dark, club-shaped cerotegument, positioned on well-developed cylindrical tubercles; two pairs of setae on centrodorsal plate, five pairs on dorsal circumnotogastral plate, three pairs of setae in p series positioned on ventral circumnotogastral plate. Opening of gla mid-way between setae lm and lp. With two pairs of lyrifissures visible dorsally. Posterior margin of dorsal circumnotogastral plate rounded, crenellated.

Ventral region. Epimeral setae setiform, thin, subequal in length, formula 3-1-2-2 ( Fig. 13 b). Microsculpture of ventral plate with elongate ridges running transversely in anogenital region, more longitudinally toward lateral margins. Genital plates slightly broader than long, striate and ridged, with six pairs of longitudinally-aligned genital setae positioned close to, but not on, medial edges; g 1 longer than others. Genital setae longer and thicker than epimeral setae. Anal setae spiniform, 19, positioned on posterior half of anal plates on small tubercles, almost their length from median edge. With three pairs of subequal, spiniform adanal setae; ad 3 positioned at least their length from margin of anal plates; mutual distance between ad 1 half that between ad 1 and ad 2. Ventral plate with shallow post-anal protuberance.

Lateral aspect. Mid-line of rostrum curved, vertical ( Fig. 12 c). Lamellar apophysis extending about a quarter of distance between base of rostral seta and anterior margin of bothridium. Hysterosoma not markedly dorsoventrally flattened. Exobothridial seta absent. Humeral process consisting of long (60) ventrallyprojecting, sharply-pointed, dagger-like spine extending as far as midpoint of acetabulum II. Centrodorsal region markedly curved.

Legs. Heterotridactylous; covered in thick cerotegument consisting of irregular plaques; porose areas on trochantera and femora. Seta l " on tibia I thick, straight, strongly barbed, club-shaped apically ( Fig. 4 c).

Solenidion φ2 on tibia I emerging from apophysis positioned on dorsal surface of apophysis of φ1. Formula Leg I: 1-4-3(1)-4(2)-14(2); Leg II: 1-4-2(1)-4(1)-14(1); Leg III: 1-2-1(1)-3(1)-13; Leg IV: 1-2-1(1)-3(1)-12.

Material Examined. Holotype, two paratype females and two paratype males, ex. foliage of Banksia ilicifolia and Nuytsia floribunda, Jandakot Airport, Perth , Western Australia, coll. R.A. Tassone, 8.i.1995. One paratype female, ex. fogging of Nuytsia sp., nr. Perth, Western Australia, coll. J.D. Majer. More details of habitat and sampling methods in Banksia woodland at Jandakot Airport can be found in the paper by Tassone & Majer (1997).

Etymology. The specific name tuberculosus refers to the microsculpture of the centrodorsal region.

Remarks. Scapheremaeus tuberculosus sp. nov. differs from other members of the genus by the following combination of characters: 1) the large, well-developed centrodorsal tubercles; 2) the long, sharp, dagger-like humeral process; 3) well-developed lamellar apophysis and presence of translamellar ridge but only a faint transbothridial ridge; 4) very long, well-developed seta g 1, longer than epimeral setae; 5) head of sensillus large, elongate, smooth; 5) lateral depressions either side of the lenticulus; 6) large tubercles in the centrodorsal region.

Scapheremaeus tuberculosus sp. nov. is a member of the Carinatus species-group. It is closest morphologically to S. allmani sp. nov. with which it shares the long, pointed humeral processes, the tuberculate centrodorsal region and the elongated apophyses of the lamellar setae. It differs in that the lamellar apophyses do not project as far as the rostrum, the head of the sensillus is smooth, not spinose and the rostrum is blunt, not acute.

Figures

FIGURE 12. Scapheremaeus truncatus sp. nov. a) dorsal; b) ventral; c) lateral.

FIGURE 13. Scapheremaeus tuberculosus sp. nov. a) dorsal; b) ventral; c) lateral.

FIGURE 4. a) Scapheremaeus baylyi sp. nov., circumnotogastral plates, viewed ventrally (centrodorsal plate removed); b – e) tibiae I (right, antiaxial); b) Scapheremaeus allmani sp. nov., showing cerotegument; c) Scapheremaeus tuberculosus sp. nov.; d) Scapheremaeus alisonae sp. nov.; e) Scapheremaeus bulbosensillatus sp. nov.