Scapheremaeus alisonae, 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 : 3-5

Scapheremaeus alisonae sp. nov.

( Figs. 1 , 4 )

Dimensions. holotype female: length 417, breadth 217; paratype male: length 373, breadth 192; paratype female: length 429, breadth 213. Ratio of length of prodorsum to total length (holotype): 0.23.

Prodorsum. Rostrum rounded; rostral seta straight, spiniform, 12 ( Fig. 1 a). Lamellar seta setiform, 14, covered in cerotegument rendering it club-shaped, on short, broad tubercles. Interlamellar seta absent. Costula curving medially from anterior of bothridium; connecting proximally with narrow trans-bothridial ridge. Lateral carina absent. Bothridium with well-developed rim; sensillus club-shaped, head dark, smooth, diameter 20. Prodorsum tuberculate.

Notogaster. Length 320. Circumdorsal scissure entire, with diagonal extensions into humeral region ( Fig. 1 a). Lenticulus sub-rectangular with thick rim (diameter 22). Centrodorsal region 251 long, 147 broad, rounded posteriorly, with microsculpture consisting of tubercles arranged in lines forming a tessellated pattern. Ten pairs of smooth, bacilliform notogastral setae with club-shaped cerotegumental covering, on short tubercles ( Fig. 1 d). Centrodorsal plate pear-shaped, broadest at level of gla, bearing two pairs of setae, lm and lp, positioned laterally. With slight centrodorsal ridge becoming more prominent on posterior part of centrodorsal plate ( Figs 1 a, 1c) and with shallow posteriolateral depressions. Dorsal circumnotogastral plate with sparingly plicate pattern; plications consisting of tubercles arranged in lines; with five pairs of setae: c 2 (11) in humeral region, posterior of lyrifissure ia; seta la posteriolateral to c 2; h series positioned on rounded caudal region; ventral circumnotogastral plate with two pairs of setae belonging to p series, not visible in dorsal view.

Ventral region. Epimeral setae setiform, sub-equal, formula 3-1-2-2, seta 4a 21 ( Fig. 1 b). With six pairs of genital setae, subequal in length, 13–17, all in alignment, positioned close to, but not on, medial edges of genital pates. Each genital plate with longitudinal lines of tuberculate microsculpture; plates surrounded by thickened ridge. Posterior part of ventral plate consisting of tubercles arranged in lines forming a tessellated pattern. Anal setae subequal, 12, positioned away from median edge of anal plates, and on posterior half of plates. With only two pairs of adanal setae (ad 3 absent), spinose, sub-equal, 10; positioned posterior of anal plates and adjacent to them. Each anal plate with longitudinal lines of small tubercles. Circumgastric scissure crenellated posterior of anal plates. With only two pairs of bacilliform setae in p series, with club-shaped cerotegument.

Lateral aspect. Rostrum ventral of seta ro vertical; lamellar seta positioned two-thirds of the distance between bothridia and bases of seta ro ( Fig. 1 c). Prodorsum densely tuberculate. Exobothridial seta absent. Humeral process broad, shallow, triangular. Lenticulus projecting slightly above dorsum. Shallow centrodorsal ridge extending from just posterior of lenticulus as far as caudal margin of circumdorsal scissure.

Legs. Heterotridactylous; covered in thick cerotegument consisting of elongated ridges; porose areas on trochantera and femora. Seta l " on tibia I spiniform, thick, straight, barbed ( Fig. 4 d). 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).

Material examined. Holotype female, one paratype male, one paratype female, in leaf litter, remnant mallee eucalypt vegetation (35° 6'55.10"S 142° 2'43.69"E), Mallee Research Station, Walpeup, Victoria, coll. M.J. Colloff, 31.v.1994.

Etymology. This species is named after my partner, Alison Jean Killen.

Remarks. Scapheremaeus alisonae sp. nov. differs from other members of the genus by the following combination of characters: 1) two pairs of adanal setae; 2) two pairs of setae in p series positioned on ventral circumnotogastral plate, thus nine pairs of notogastral setae; 3) costulae converging apically, without an anterior transcostular ridge; 4) lamellar setae on tubercles positioned half the distance between the apices of the costulae and the rostral setae; 5) microsculpture of centrodorsal and ventral plates consisting of tubercles arranged in lines forming a tessellated pattern; 6) with a crenellated circumgastric scissure in the region posterior of the anal plates.

Scapheremaeus alisonae sp. nov. is a member of the Carinatus species-group ( Colloff, 2009), based on the presence of lateral carinae and humeral extensions of the circumnotogastral scissure. It is one of only three members of the group with nine pairs of notogastral setae (missing seta p 3), and two pairs of adanal setae (missing seta ad 3), the others being S. nivalis sp. nov. and S. zephyrus sp. nov. (cf. remarks for these species below). Scapheremaeus alisonae sp. nov. is morphologically most similar to these species in notogastral setation, but is more similar to S. cheloniella Colloff, 2009 in the pattern of microsculpture of its centrodorsal, circumnotogastral and ventral plates. Scapheremaeus cheloniella is also from mallee eucalypt vegetation, about 200 km northwest of the type locality of S. alisonae sp. nov.

Figures

FIGURE 1. Scapheremaeus alisonae 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.