Spineremaeus smithi, 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 : 21-25

Spineremaeus smithi sp. nov.

(Figs. 1, 2)

Dimensions. Holotype female length 410 μm, breadth 252 μm. Paratype female lengths 462, 441 μm, breadths 267, 265 μm. Paratype males (n = 10) mean length 403 μm (range 378–413 μm), breadth 247 μm (range 236–254 μm). Ratio of length of prodorsum to total length: 0.23 (holotype).

Female. Prodorsum: Rostrum rounded, rostral setae (ro) 28 μm long, spiniform, emerging from squat tubercles (Fig. 1c). Lamellar seta 12 μm long, straight, spiniform. Apophysis of lamellar seta (le) 38 μm long, extending beyond rostrum, expanded basally, apophyses converging apically (Fig. 1a), emerging from apices of straight, slightly converging costulae. Lateral carinae absent. Anterior trans-costular ridge connecting bases of lamellar apophyses. Interbothridial (posterior trans-costular) ridge entire, well-developed, bearing prominent circular apophyses of interlamellar setae, each with a projecting rim. Interlamellar seta (in), long (58 μm), thick, sparingly barbed, pointed, extending anteriorly almost as far as rostrum. Bothridium with broad rim (46 μm diameter); bothridial seta (bs) club-shaped, stalk 18 μm long, head 25 μm long 18 μm broad, tuberculate, darkly pigmented. With pair of short longitudinal ridges posterior of each bothridium, medial ones connecting with interbothridial ridge, and delimiting rectangular posteriomedial region with slight medial ridge indicated by parallel lines of tubercles. Prodorsum with well-developed tubercles, densest on lateral regions and on margins of carinae, sparingly distributed medially.

Notogaster: Length 343 μm; ratio of length to breadth 1.22; notogaster broad, oval. Circumdorsal scissure absent (Fig. 1a). Humeral processes well-developed and visible in dorsal view (cf. lateral aspect, below). Lenticulus 45 μm long, 45 μm broad, bulbous, surrounded by oval ridge of cuticle, broader than long, with digitate margin. Notogaster with dense tubercles laterally, becoming sparsely distributed on centrodorsal region; with conically spinose cerotegument (Fig. 1d). Ten pairs of smooth notogastral setae on short tubercles; setae of c and l series spiniform, those of h and p series with club-shaped cerotegumental covering. Setae sub-equal in length (10–16 μm), on squat tubercles. Seta c 2 just medial of lyrifissure ia; c 3 positioned on humeral region. Elongated, sub-oval ridge in centrodorsal region, with strongly crenellated margin, extending from just posterior of lenticulus to point level with lyrifissurae ips. Region enclosed by centrodorsal ridge with a series of longitudinal lines of tubercles and containing setae lm on lateral margin of central region, medial of transverse lyrifissurae im, and setae lp posteriorly.

Ventral region: Seta h on mentum very long (35 μm) setiform. Epimeral setae setiform, formula 3-1-2-2; 1b, 3b and 4a considerably longer (31–35 μm) than others (Fig. 1b). Genital plates oval, with faint striae; each plate 70 μm long, 33 μm broad, with six setae; g 1 positioned lateral of g 2-6; g 1 longer than others. Aggenital seta spiniform, 15 μm long. Ventral plate tuberculate, ventral margin of notogastral plate folded ventrally covering circumgastric scissure (cgs), broadly V-shaped. Anal plates hexagonal, tuberculate; anal setae spiniform, 16 μm long. Adanal setae spiniform, sub-equal in length to anal setae; ad 1-2 positioned on ridge immediately posterior of anal plates; mutual distance between ad 1 slightly less than their length, subequal to that between ad 1 and ad 2; ad 3 positioned 2.5 × this distance anteriolaterally.

Lateral aspect: Rostrum slightly concave dorsal and ventral of rostral seta; lamellar apophyses separated from prodorsum for their entire length (Fig. 1c). Interlamellar seta projecting vertically. Lenticulus bulbous, prominent, projecting above dorsum; dorsal region of lenticulus protruding further posteriorly than its base. Humeral process (hp) elongated, lath-like, slightly curved posteriorly, rounded distally, 58 μm long, 12 μm broad, extending as far as ventral facies of acetabula II and III. Centrodorsal region of notogaster from posterior of lenticulus to position level with setae h 3 and p 3 strongly domed, prominent. Lateral region shelf-like posterior of setae h 3 and p 3. Setae of p series dorsal of circumferential scissure (cf).

Legs: Monodactylous ( Fig. 2 ). Formulae: Leg I: 0-4-4(1)-4(2)-11(2); Leg II 0-4-4(1)-3(1)-11(2); Leg III 1-2 - 1(1)-2(1)-13; Leg IV 0-2-1(1)-2(1)-13. With pori on axial surface of femora I-IV and posterioventral region of tarsi I-IV. Lengths of leg segments (femur to tarsus): Leg I: 125, 34, 66, 41 μm; Leg II: 105, 26, 53, 32 μm; Leg III: 78, 21, 53, 39 μm; Leg IV: 86, 22, 63, 42 μm. Tarsus I squat, sub-triangular, only slightly longer than broad. Solenidion φ2 of tibia I positioned on dorsal surface, some distance posterior of apophysis of solenidion φ1 ( Fig. 2 a). Seta l " on tibia I and ft ' on tarsus IV stout, elongate, with clavate cerotegument apically ( Figs. 2 a, 2d); seta d on femur IV, long, curved, stout ( Fig. 2 d).

Material examined. Holotype female, seven paratype males, 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. One paratype male, ANIC 3506, trough of flight intercept trap, Maurge Jowett’s [garden] (Red Road), Norfolk Island, 29° 0'37.73"S, 167°56'43.49"E, ca. 250 m., coll. 1.ii.1985. Two paratype females, 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. Two paratype males, ANIC 3511, trough of flight intercept trap, Red Road Track, Norfolk Island National Park, 29° 01'S, 167°57'E, coll. M. Christian, 17.iv.1985. Holotype and paratypes deposited in the Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species is named in honour and memory of my dear friend and colleague, the late Professor Huw Vaughan Smith (Scottish Parasite Diagnostic Laboratory, Stobhill Hospital, Glasgow), in recognition of his contribution to research in parasitology.

Remarks. Spineremaeus smithi can be differentiated from other species of Cymbaeremaeidae on the basis of the diagnostic characters of the genus (cf. above). In addition, Sp. smithi has other characters that are probably autapomorphic within the Cymbaeremaeidae that have not been included in the generic diagnosis. The reason for not including these characters is because my intent is to make the generic description broad and inclusive, given that the genus Spineremaeus is monotypic and the Cymbaeremaeidae of the South-west Pacific are very incompletely known. Also, autapomorphy cannot be confirmed where characters are on legs, for example, which have been described for less than a third of named species of Cymbaeremaeidae . These other, putative, autapomorphic characters include: 1) The spiny, conical cerotegument; 2) 11 setae on tarsus I. Reduced setation on tarsus I is found in Scapheremaeus rustenburgensis Engelbrecht, 1975 (12 setae), Glanderemaeus hammerae Balogh & Csiszár, 1963 (10 pairs) and Seteremaeus spinosus Hammer, 1971 (9 pairs). All other Cymbaeremaeidae for which leg chaetotaxy is known have 20 setae ( Ametroproctus Coropoculia and Scapuleremaeus ), 17 ( Bulleremaeus ), 16 ( Cymbaeremaeus ) or 14–15 ( Scapheremaeus ); 3) four setae on genua I and II, whereas other Cymbaeremaeidae have 0–3 setae on genu I and 1–3 on genu II; 4) the thick, elongated, curved seta d on femur IV; 5) with epimeral setae 1b, 3b and 4a considerably longer than the other epimeral setae; 6) with solenidion φ2 of tibia I not located on the apophysis of solenidion φ1 but positioned some distance posterior of it.

FIGURE 1. Spineremaeus smithi gen. et sp. nov., holotype female; a) dorsal; b) ventral; c) lateral; d) detail of seta h 1 and cerotegument.

In terms of morphological similarities, it was mentioned in the remarks section on the genus Spineremaeus that the absence of a circumdorsal scissure is shared with species of the Emarginatus species-group of Scapheremaeus . Of these species, Sc. walteri Colloff, 2010 from Australia differs from the rest in having only seven pairs of notogastral setae (the p series are absent), Sc. morenoi from Cuba differs from the rest in that the bothridial seta has a broad, asymmetric head and the centrodorsal plate is striated. Scapheremaeus striatomarginatus Hammer, 1979 from Java has the rostral and lamellar setae reduced or absent or folded ventrally (it is not apparent which from the original description), reduced notogastral setation and an elongated head to the bothridial seta. Scapheremaeus emarginatus Hammer, 1966 from New Zealand, like Spineremaeus smithi , has ten pairs of notogastral setae and in similar configuration, especially lm and lp, though the former species lacks lamellar apophyses and the rostral setae are either reduced, absent or folded ventrally. The latter character state is found in Sc. pinguis sp. nov. (cf. below) which, like Sc. smithi has well-developed lamellar apophyses; a broad, oval notogaster; long humeral processes (absent in other members of the Emarginatus species-group) and ten pairs of notogastral setae. However, in Sc. pinguis seta lp is not in the centrodorsal position and setae of the p series are positioned ventrally. Nevertheless, Spineremaeus smithi can be considered most morphologically similar to this species.

Figures

FIGURE 2. Spineremaeus smithi gen. et sp. nov., paratype female; a) right leg I, axial; b) left leg II, anti-axial; c) left leg III anti-axial; d) left leg IV, anti-axial. Pori are on axial surfaces.