Crotonia norfolkensis, Colloff, Matthew J., 2010

Colloff, Matthew J., 2010, New species of Crotonia (Acari: Oribatida: Crotoniidae) from Lord Howe and Norfolk Islands: further evidence of long-distance dispersal events in the biogeography of a genus of Gondwanan relict oribatid mites, Zootaxa 2650, pp. 1-18 : 7-9

Crotonia norfolkensis sp. nov.

(Figs. 4, 8b)

Dimensions: holotype female length 1027, breadth 426. Ratio of length of prodorsum to total length: 0.36.

Description of female. Prodorsum: ratio of length to breadth 1.18. Rostrum with well-developed naso with lateral edges incised; rostral seta very short (12), straight, spiniform, smooth, on short tubercle (Fig. 4a). Lamellar seta 188, recurved, smooth. Lamellar apophyses 102, straight, thin, cylindrical, parallel, three quarters as long as their mutual distance, extending anteriorly beyond apices of rostral setae. Interlamellar apophysis as long as broad; interlamellar seta slender, 310, smooth, extending anteriorly beyond apical curve of lamellar setae. Prodorsal ridges extending a third of the distance between bases of interlamellar and lamellar apophyses. Diameter of bothridium 43; lateral ridge of bothridium in the form of blunt, D-shaped lobe with a flat, narrow posterior ridge; hexagonal reticulations of operculum smooth, with no common point of origin near lateral margin ( Fig. 8 b). Inter-bothridial ridge with shallow curve, indented medially; median field of muscle sigilla present. Prodorsal microsculpture smooth, porose.

Notogaster: ratio of length of notogaster to breadth of notogastral shield 1.61; notogastral shield broadest at level of bases of setae e 2 (Fig. 4a); ratio of width of shield to entire notogastral width 0.78; lateral margins of opisthosoma inflated, sub-lozenge-shaped, with well-developed diagonal ridge on pleuraspis lateral of seta e 2. Dorsosejugal suture discrete, simple. Pre-notogastral shield with indented posteriolateral margins at level of long (33), cylindrical apophyses of setae c3; anteriolateral margins sloping medially. With 13 pairs of notogastral setae: c 3 flagelliform, long (188) extending anteriorly as far as bothridium; seta c 1 (44) on short tubercle on posterior margin of pre-notogastral shield. Distance between bases of c 1 equal to that between c 1 and c 3. Lyrifissure ia located immediately posteriolateral of apophyses of setae c 3. Notogastral shield relatively narrow, smooth, porous, elongated; sides slightly convex, converging posteriorly. With welldeveloped lateral hyaline strip (suprapleural scissure) bearing squat tubercles of setae cp and e 2. Notogastral shield bordered laterally by relatively narrow strips of small tubercles, ca. 2–3 tubercles wide; otherwise shield smooth, porose. Apophysis of seta f 2 conical, well-developed, projecting beyond margin of notogastral shield. Seta cp short (88), curved, setiform; d 2 short (17), straight, setiform; distance between them the same as between setae c 1. Seta e 2 markedly shorter (33) than c 1. Opisthosomal gland opening gla positioned anteriomedial of short (55), recurved seta f 2 with its tubercle projecting beyond notogastral margin. Caudal apophyses in paired bilateral clusters, originating directly from caudal margin. Apophysis of f 1 curved dorsolaterally (22), separated from base of that of h 1 by distance of at least its width; apophysis of seta h 1 (30) projecting posteriorly; those of h 2 (36) directly ventral and medial of h 1, parallel, projecting posteriorly, mutual distance twice their length; apophysis of seta h 3 (22) positioned ventrally between those of h 1 and f 1. Caudal margin between apophyses of setae h 2 straight, transverse. Caudal setae all recurved, sparsely barbed f 1 44, h 1 78, h 2 83, h 3 45, not visible in dorsal view.

Crotonia norfolkensis . holotype female a) dorsal; b) ventral.

Ve nt er: epimeral microsculpture smooth, porose (Fig. 4b); epimeral setae smooth, spiniform, formula 3-1- 4-3; 3c elongated, recurved, on long apophysis, otherwise epimeral setae subequal (ca. 17–28). Lateroventral circumgastric scissure (lcs) broad, curved, forming a strongly obtuse angle (ca. 140°) with broad, curved perianal circumgastric scissure (pcs). Anteriolateral margin of adanal plate at junction of lcs and pcs indented. Genital plates sub-circular; posterior margin transverse; posteriolateral margins straight, diverging. Perigenital region sparsely smooth, porose. Each genital plate 185 long, 100 broad with eight spiniform setae, subequal in length (22–30); two pairs of aggenital setae, subequal in length to genital setae. Anal plate 50 broad, 254 long, with three very short (14), fine setae distributed on posterior half of plate; three pairs of short, fine adanal setae, ad 2-3 slightly shorter (19) and thinner than spiniform stout ad 1 (30). Distance between ad 2 and ad 3 half that between ad 2 and ad 1. Ventral margin of notogaster surrounding anal plates U-shaped. Setae p 1 reflexed, short (33) on short apophyses, their mutual distance the same as their length; p 2-3 curved, subequal (30).

Material examined. Holotype female, QM S26077 , pyrethrum knockdown, rainforest, Mount Pitt Reserve, Norfolk Island, 29°0'52.04"S 167°56'3.63"E, ca. 230 m., coll. G.B. Monteith, 26–30.xi.1979. Type deposited in Queensland Museum, Brisbane.

Etymology. This species is named for its type locality, Norfolk Island.

Remarks. Crotonia norfolkensis differs from all other Crotonia spp. by the following combination of characters: 1) the extremely short rostral setae; 2) the relatively short apophyses of setae h 2 and separated apophyses of setae f 1 and h 1; 3) the epimeral setal formula 3-1-4-3; 4) the very long, recurved setae 3c and their prominent apophyses; 5) the incurved posteriolateral margins and medially sloping anteriolateral margins of the pre-notogastral shield; 6) setae h 3 and their apophyses on ventral basal surface of those of h 2 and not visible in dorsal view; 7) seta e 2 is considerably shorter than cp and f 2; 8) the caudal setae are sparingly barbed.

Crotonia norfolkensis is a member of the Cophinaria species-group (sensu Colloff, 2009b). It is morphologically most similar to C. brachyrostrum ( Hammer, 1966) from New Zealand. Luxton (1982) made C. brachyrostrum a junior synonym of C. cophinaria ( Michael, 1908) , but this decision was not accepted by Colloff (2009a) because it was not based on an examination of type material and the morphological differences between them are more than can be explained just by variation. Both C. norfolkensis and C. brachyrostrum have setae c 3 extending as far as the bothridia; similar dimensions and arrangement of the caudal apophyses, with those of f 1 and h 1 separate and those of h 2 relatively short and parallel and those of h 3 shorter than the others and not visible in dorsal view; the relatively short setae p 1 and with setae e 2 shorter than cp and f 2. Crotonia norfolkensis also shares the former two character states with C. wallworki Colloff, 2009 from Chile. Crotonia norfolkensis differs from C. brachyrostrum in that the caudal region between apophyses of setae h 2 is straight rather than U-shaped; setae d 2 are shorter, and the notogastral shield has narrow lateral strips of tubercles.

Figures

FIGURE 8. Bothridia a) Crotonia gorgonia sp. nov.; b) Crotonia norfolkensis sp. nov.; c) Crotonia utricularia sp. nov.