Scapheremaeus pinguis, Colloff, Matthew J., 2011

Colloff, Matthew J., 2011, A new genus of oribatid mite, Spineremaeus gen. nov. and three new species of Scapheremaeus (Acari: Oribatida: Cymbaeremaeidae) from Norfolk Island, South-west Pacific, and their biogeographical affinities, Zootaxa 2828, pp. 19-37 : 31-33

Scapheremaeus pinguis sp. nov.

( Figs. 7 , 8 )

Dimensions. Holotype female length 498 μm, breadth 293 μm. Paratype female, length 510 μm, breadth 321 μm. Paratype male length 466 μm, breadth 287 μm.

Female. Prodorsum: Rostrum acute, projecting beyond prodorsum, 9 μm long, 18 μm broad, with lateral constrictions ( Fig. 7 a). Rostral seta (ro) barely visible in dorsal view, projecting ventrally (cf. lateral aspect below), 13 μm long, spiniform, emerging from squat tubercle on ventral surface of rostrum. Lamellar apophyses long (43 μm), curved, broadened basally, converging apically, without transverse ridge connecting their bases; positioned at apices of curved, converging costulae. Lamellar seta (le) 8 μm long, bacilliform, incurved. Well-developed curved carinae, acute at lateral apices, connected anteriorly by transverse ridge and posteriorly with costulae. Interbothridial ridge in form of shallow inverted V, with posterior transverse ridge bearing bacilliform interlamellar setae (in) (6 μm long) on squat tubercles. Bothridium with broad rim (32 μm diameter); bothridial seta (bs) club-shaped, stalk 25 μm long, head 23 μm long 15 μm broad, barbed, darkly pigmented. Prodorsum tuberculate lateral of carinae, smooth anteriorly and with polygonate alveoli in median region.

Notogaster: Length 375 μm; ratio of length to breadth 1.22; notogaster broad, oval. Circumdorsal scissure absent ( Fig. 7 a). Dorsosejugal suture transverse medially, with shallow lateral concave regions laterally as far as posterior of bothridium. Humeral process well-developed, bi-lobed, visible in dorsal view (cf. lateral aspect, below). Lenticulus 34 μm long, 38 μm broad, surrounded by oval ridge of cuticle. Notogaster with polygonal pattern of ridges and alveoli; caudal margin with ridges and crenellations. Ten pairs of smooth, bacilliform setae on broad, well-developed tubercles. Seta c 2 posterior of lyrifissure ia; la just posteriolateral to c 2; lm on centrodorsal region, lp on lateral margin anterior of h 3. Notogastral setae sub-equal in length (8–10 μm); those of p series positioned on ventral portion of notogastral plate: not visible in dorsal view (cf. ventral region, below).

Ventral region: Seta h on mentum 18 μm long, thin, setiform ( Fig. 7 b). Epimeral setae setiform, formula 3-1-2- 2; seta 4a longer (14 μm) than others (7–13 μm). Genital plates oval, with faint striae; each plate 68 μm long, 35 μm broad, with six setae; seta g 1 in line with setae g 2-6, longer than others. Aggenital seta spiniform, 13 μm long. Ventral plate alveolate posteriolaterally, with elongated plaques anteriorly. Ventral margin of notogastral plate folded ventrally covering circumgastric scissure (cgs), with setae of p series on well-developed conical tubercles; notogastral margin broadly V-shaped, incised medially; incision surrounded by U-shaped ridge. Anal plates subhexagonal, alveolate; anal setae setiform, 8–10 μm long. Adanal setae spiniform, 6–10 μm long; ad 1-2 positioned adjacent to and posterior of anal plates; mutual distance between ad 1 subequal to that between ad 1 and ad 2; ad 3 positioned 3 × this distance anteriolaterally.

Lateral aspect: Hysterosoma strongly dorsoventrally flattened: dorsal and ventral surfaces more or less parallel. Rostrum protruding and prominent; rostral seta emerging from ventral surface of rostrum; lamellar apophyses separated from prodorsum for their entire length ( Fig. 7 c). Lenticulus bulbous, projecting above dorsum. Humeral process (hp) elongated (48 μm), relatively broad (21 μm), curved longitudinally (thus appearing bi-lobed in dorsal view), rounded distally, extending as far as mid-point between acetabula II and III. Centrodorsal region of notogaster from posterior of lenticulus to caudal margin; flat, elongated. Setae of p series positioned ventral of circumferential scissure (cf).

Legs: Monodactylous; leg segments with ridged, polygonate cerotegument ( Fig. 8 ). Formulae: Legs I: 0-4- 2(1)-4(2)-15(2); Legs II 0-4-2(1)-4(1)-14(1); Legs III 1 -0-1(1)-4(1)-14; Legs IV 0-0-1(1)-3(1)-13. Lengths of leg segments (femur to tarsus): Leg I: 97, 35, 79, 30 μm; Leg IV: 92, 29, 76, 47 μm. Tarsus I squat, sub-triangular, only slightly longer than broad. With pori on axial surface of femora I–IV. With solenidion φ2 of tibia I emerging from apex of apophysis of solenidion φ1. Seta l " on tibia I stout, elongate, with clavate cerotegument apically ( Fig. 8 a); seta ft ' on tarsus IV long, stout, spiniform ( Fig. 8 b).

Material examined. Holotype female, ANIC 3505, trough of flight intercept trap, Filmy Fern Gully, Norfolk Island National Park, 29°01'S, 167°57'E, ca. 180 m., coll M. Christian, 17.iv.1985. Paratype female, ANIC 3509, trough of flight intercept trap, Red Road Track, Norfolk Island National Park, 29° 01'S, 167°57'E, coll. M. Christian & C. Baker, 8.ii.1985. Paratype male, ANIC 3511, same data as 3509 but coll. M. Christian, 17.iv.1985. Holotype and paratypes deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. The specific name, pinguis , is Latin for ‘fat’, alluding to the corpulent hysterosoma of this species.

Remarks. Scapheremaeus pinguis sp. nov. differs from other members of the genus by the following combination of characters: 1) the absence of a circumdorsal scissure; 2) seta lm located on centrodorsal region of notogastral plate, with la and lp located laterally; 3) notogastral setae all bacilliform, those of h series and lp located on prominent tubercles on undulating caudal margin of notogaster; 4) notogaster with polygonate alveoli and ridges; 5) with long, incurved lamellar apophyses; 6) prominent rostrum; 7) rostral setae curved ventrally, emerging from ventrally positioned tubercles; 8) anal plate alveolate; 9) setae of the p series on ventral part of notogastral plate; ventral margin of notogastral plate incised medially, and the incision surrounded by a U-shaped ridge; 10) the absence of setae on femur IV.

Like Spineremaeus smithi , Scapheremaeus pinguis has no circumdorsal scissure. It is a member of the Emarginatus group. Scapheremaeus pinguis shares with Sc. striatomarginatus Hammer, 1979 (Java) the location of seta lp on the caudal margin anterior of seta h 3. However, this latter species differs from Sc. pinguis in lacking well-developed lamellar apophyses, lamellar and interlamellar setae. Of the members of the Emarginatus group, Sc. pinguis is closest morphologically to Sc. emarginatus Hammer, 1966 from New Zealand, with which it shares the bi-lobed humeral processes (in dorsal view), polygonate alveolate notogaster, well-developed lateral carinae and undulating caudal margin of the notogaster, but differs in the short lamellar apophyses and having seta lp in the centrodorsal position.

Figures

FIGURE 7. Scapheremaeus pinguis sp. nov., holotype female; a) dorsal; b) ventral; c) lateral.

FIGURE 8. Scapheremaeus pinguis sp. nov., paratype female; a) left leg I, anti-axial; b) left leg IV, anti-axial. Pori are on axial surfaces.