Scapheremaeus notoverrucatus, 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 : 20-22

Scapheremaeus notoverrucatus sp. nov.

( Fig. 10 )

Dimensions. Holotype female: length 444, breadth 227; paratype females: mean length (n = 4) 425 (range 390-442), mean breadth 228 (range 207-245); paratype males: lengths 414, 429, breadths 225, 222. Ratio of length of prodorsum to total length (holotype): 0.18.

Prodorsum. Rostrum acute, with sparse, shallow alveoli. Rostral seta minute (8), straight, spiniform ( Fig. 10 a). Lamellar seta minute (5) bacilliform, emerging from concave socket in centre of broad, squat tubercle positioned at apex of costula. Apical trans-costular ridge narrow and faint; medial ridge well-developed, entire. Costulae slightly sloped anteriomedially, extending posteriorly to point anterior of bothridia. Lateral margins of prodorsum with shallow alveoli. Narrow interbothridial ridge present. Interlamellar seta absent. Inter-costular region smooth. Sensillus with large, smooth, club-shaped, darkly-pigmented head, ca. 23 long, 21 broad, emerging on short stalk from bothridium (diameter 20) with large thick rim, abutting dorsosejugal suture.

Notogaster. Length 347. Circumdorsal scissure entire, oval ( Fig. 10 a). Lenticulus oval, wedge-shaped (28 long, 22 broad) with discrete margin, surrounded by complex pattern of ridges. No humeral process visible. Centrodorsal plate 260 long, 175 broad, oval, broadest at level of lp. Without well-developed posterior centrodorsal ridge or posteriolateral concavities. Centrodorsal microsculpture consisting of elongate thin irregular centrodorsal ridge with narrow transverse curved ridges ( Fig. 10 a). Cuticle smooth otherwise. Posterior centrodorsal region with slight lateral indentations. Dorsal circumnotogastral plate sparingly plicate. With ten pairs of notogastral setae; those of the c and l series on raised verrucae surrounded by circular ridges. Setae of c, l and h series bacilliform, short (ca. 8-10), without cerotegument ( Fig. 10 d). Two pairs of setae on centrodorsal plate, five pairs on dorsal circumnotogastral plate; with three pairs of spiniform setae in p series, positioned on ventral circumnotogastral plate. Opening of gla prominent, on dorsal circumnotogastral plate posteriolateral of seta lm. With three pairs of lyrifissures visible dorsally. Posterior margin of dorsal circumnotogastral plate rounded.

Ventral region. Epimeral setae setiform, those on epimere I longer than others; formula 3-1-2-2 ( Fig. 10 b). Microsculpture of ventral plate with irregular transverse ridges between anal and genital plates, plaques in the epimeral region and shallow alveoli posteriolaterally. Sub-rectangular striate genital plates slightly longer than broad, with six pairs of genital setae positioned close to, but not on, medial edges of plates. Seta g 1 positioned lateral of g 2-6. Arcuate ridge anterior of genital plates, with setae 4a at either end. Aggenital setae positioned laterally of setae g 6. Anal setae spiniform, 8, positioned on posterior halves of foveolate anal plates, at least their length from the median edge. With three pairs of spiniform adanal setae. Posterior margin of circumgastric scissure rounded.

Lateral aspect. Mid-line of rostrum projecting anteriorly ( Fig. 10 c). Hysterosoma dorsoventrally flattened. Exobothridial seta absent. Humeral process vestigial, consisting of a minute triangular projection. Lenticulus prominent, projecting well above dorsum.

Legs. Heterotridactylous.

Material Examined. Holotype female and two paratype females, ex. litter, Eucalyptus forest, Old Farm Road, Mt. Wellington (42°54´S, 147°14´E), Tasmania, coll. P. Greenslade, 20.vii.1989 [TAS-183]. Two paratype males, two paratype females, ex. lichens in supralittoral zone, Green Cape (37°16´S, 150°03´E), south of Eden, New South Wales, coll. J.C. Otto, 28.i.1995. Two paratype females, in moss on river bank, 100 m. upstream of road bridge (C604), Suggan Buggan (36°57´07″S, 148°19´31″E), 388 m., Victoria, coll. M.J. Colloff, 17.iii.1996.

Etymology. The specific name notoverrucatus refers to the raised, verrucate microsculptural ridges surrounding the centrodorsal setae.

Remarks. Scapheremaeus notoverrucatus sp. nov. differs from other members of the genus by the following combination of characters: 1) the pattern of the centrodorsal microsculpture, consisting of a series of extended, longitudinal and transverse irregular ridges and finer lines, but lacking tubercles or foveolae; 2) the circular raised ridges around the setae of the c and l series; 3) the sparsely-distributed alveoli of the prodorsum and lateral margins of the ventral plate; 4) the minute, bacilliform lamellar setae and their large, broad tubercles; 5) the narrow, elongate lenticulus; 6) the smooth head of the sensillus, and 7) the vestigial humeral process.

Scapheremaeus notoverrucatus sp. nov. is a member of the Petrosus species-group. Like other members it has a complete, oval circumnotogastral scissure, lacking humeral extensions. The trapezoid arrangement of costulae, interbothridial and interlamellar ridges is similar to S. euthemellus sp. nov. and S. truncatus sp. nov., but the characteristic centrodorsal microsculpture of elongate narrow ridges and with circular ridges around the setae is rare. Only S. latus Mahunka, 1985 from Guadeloupe has a similar pattern.

Figures

FIGURE 10. Scapheremaeus notoverrucatus sp. nov. a) dorsal; b) ventral; c) lateral; d) seta c.