Crotonia brisbanensis, Colloff, Matthew J., 2010

Colloff, Matthew J., 2010, The Gondwanan relict oribatid genus Crotonia (Acari: Oribatida: Crotoniidae) from rainforests in Queensland and Northern New South Wales: new species show a mixed pattern of short-range and long-range endemism, Zootaxa 2649, pp. 1-51 : 9-11

Crotonia brisbanensis sp. nov.

( Figs. 3 , 18 c, 21)

Dimensions: holotype female length 1390, breadth 624. Paratypes: females (n = 11), mean length 1255 (range 1169–1390); mean breadth 615 (range 569–672); males (n = 13) mean length 1025 (range 980–1106), mean breadth 454 (range 411–490). Ratio of length of prodorsum to total body length: 0.33 (holotype).

Description of female. Prodorsum: ratio of length to breadth 1.12. Rostrum with squat naso, barely projecting beyond rostrum; lateral edges parallel; rostral seta 60, straight, spiniform, smooth ( Fig. 3 a). Lamellar seta 317, recurved, barbed, flagelliform apically. Lamellar apophyses 136, straight, thin, parallel, shorter than their mutual distance by a quarter; extending anteriorly beyond apices of rostral setae. Interlamellar apophyses twice as long as broad; interlamellar seta 485, flagelliform, smooth; extending anteriorly beyond apex of curve of lamellar setae. Prodorsal ridges curved medially, extending anteriorly almost half the distance between bases of interlamellar and lamellar apophyses. Diameter of bothridium 54; auriculate ridge narrow, crenellated, with indented outer margin and pair of small, blunt, anterior projections ( Fig. 18 c); hexagonal reticulations of operculum smooth and with point of origin near lateral margin. Interbothridial ridge a shallow, well-defined curve with a slight median invagination. Median field of muscle sigilla present. Prodorsal microsculpture smooth, porose with region of cuticular plaques posterior of interbothridial ridge. Prodorsum splaying posteriolaterally to form a broad triangular ridge (84 long 116 broad) extending anteriodorsally of acetabulum III.

Notogaster: ratio of length of notogaster to breadth of notogastral shield 1.52; notogastral shield broadest at level of bases of setae e 2 ( Fig. 3 a); ratio of width of shield to entire notogastral width 0.75; lateral margins of notogastral shield lozenge-shaped, inflated. Dorsosejugal suture a diffuse series of ridges. Region posterior of apophyses of setae c 3 strongly concave, waisted. Lyrifissure ia long (45) located on anterior face of large, well-developed lateral ridge (90 long, 55 wide) immediately posterior of concave region, extending onto cuticle dorsal of acetabulum III. With 13 pairs of notogastral setae (missing d 2); anterior and lateral ones smooth, caudal ones barbed. Pre-notogastral shield not evident: narrow transverse hyaline strip absent.

Apophysis of seta c 3 cylindrical, 38 long, 18 broad. Seta c 1 and c 2 setiform, short, subequal (58), on squat tubercles, extending anteriorly barely as far as dorsosejugal suture. Seta c 3 long (343), flagelliform. Notogastral shield smooth, slightly convex, tapering to V-shape anterior of caudal apophyses; bordered laterally by two narrow strips of small tubercles, extending to caudal stalk. Lateral hyaline strip (suprapleural scissure) wide, bearing tubercles of setae cp and e 2. Seta d 2 absent; setae cp and e 2 short, setiform, subequal in length (65); f 2 short (52), curved, on tubercle projecting from margin of notogastral shield. Opisthosomal gland opening gla positioned anteriomedial of seta f 2. Caudal apophyses on short, broad stalk, projecting posteriorly from caudal margin. Caudal apophyses bi-lobed, those of h 2 very long (265), irregular, inflexed at bases then diverging, slightly inflated apically. Apophysis of h 1 (32) emerging dorsolaterally from base of that of h 2; that of f 1 (45) curving dorsolaterally. Setae f 1 and h 1 short, subequal (71), barbed, flagelliform apically. Seta h 2 78, spiniform. Seta h 3 positioned anteriorly and ventrally of h 1, just visible in dorsal view.

Ve nt er: epimeral microsculpture smooth, porose ( Fig. 3 b); epimeral setae smooth, spiniform, formula 3-1- 3-3; ca. 25–35 long, 4a slightly longer (48) than others; seta 3c on well-developed tubercle. With lcs narrow, straight, transverse, forming slightly obtuse angle (ca. 110°) with pcs. Anteriolateral margin of adanal plate with narrow, shallow indentation. Genital plates circular; posterior margin rounded. Perigenital region tuberculate. Each genital plate 226 long, 130 broad, with eight setiform setae, subequal in length (30); two pairs of aggenital setae, subequal in length to genital setae. Anal plate narrow (38 broad), 330 long, with three short (19) fine setae on central region of plate; three pairs of spiniform adanal setae, ad 2-3 slightly shorter and thinner than spiniform stout ad 1 (42). Ventral margin of notogaster surrounding anal plates V-shaped. Setae of p series setiform, subequal in length (38), mutual distance between tubercles of p 1 slightly greater than length of seta p 1.

Lateral view: Caudal margin almost perpendicular to notogastral shield ( Fig. 3 c); dorsal and ventral surfaces more-or-less parallel, distance between them 474. Caudal stalk slender in lateral view, extending to level just above notogastral shield. Apophysis of seta f 1 and h 1 pointing dorsolaterally, those of h 2 horizontal, pointing posteriorly; those of h 3 positioned ventral of h 1, pointing lateroventrally. Apophysis of seta p 1 on caudal region one third of the distance from the ventral to the dorsal surface; p 2 positioned closer to p 3 than to p 1. Pleuraspis with sparse tubercles.

Material examined. Holotype female, four paratype males, QM S26063 , under logs and rocks, rainforest, Mount Brisbane, Queensland, 2705' S 15232 'E., 450 m., coll. R.J. Raven, 6.x.1979. Paratypes: eight females, five males, QM S26061 , litter, rainforest, Mount Glorious, Queensland, 27°20'7.09"S 152°46'25.14"E, ca. 570 m., coll. V.T. Davies, 7–20.vi.1974. Paratypes: one female and four males, QM S26075 , rainforest, litter, Whian Whian State Forest, New South Wales, 28°36'22.96"S 153°20'50.22"E, coll. R.J. Raven, 12.ix.1976. Paratypes: one male, two females, FM 78–133, rotted gill fungi, forest, nr. Mount Glorious, Queensland, 27°17'S 152°46'E, 800 m., coll. S. & J. Peck, 4.vii.1978. Holotype and paratypes from QM samples deposited in the Queensland Museum, Brisbane; paratypes from FM 78–133 deposited in the Field Museum of Natural History, Chicago.

Etymology. This species is named for its type locality, Mount Brisbane, Queensland.

Remarks. Crotonia brisbanensis differs from all other Crotonia spp. by the following combination of characters: 1) prodorsum with large, triangular posteriolateral ridges; 2) absence of setae d 2 and their alveoli; 3) long flagelliform setae c 3 and short, setiform setae c 1-2; 4) extensive network of plaques on prodorsum posterior of bothridium; 5) caudal apophyses on stalk, projecting horizontally at level slightly above that of notogastral shield; 6) apophyses of h 2 diverging apically; 7) setae le, f 1 and h series sparingly barbed; 8) pleuraspis with sparse tubercles; 9) Notogastral shield smooth, porose.

Crotonia brisbanensis is morphologically most similar to Crotonia maculata sp. nov. and Crotonia capistrata Luxton, 1987 . All three have long, projecting caudal apophyses on a stalk, with those of c 2 at least three times longer than the others. Crotonia brisbanensis differs from the other two species, which have a maculate notogastral shield, in having a smooth, porose shield. It differs from C. maculata in that it lacks setae d 2 or their alveoli, has barbed setae le, f 1 and h and short, setiform setae c 1-2 (c 2 is markedly longer than c 1 in Crotonia maculata ). Crotonia brisbanensis differs from C. capistrata in that it has only sparse tubercles on the pleuraspis and has much longer setae c 1-2 - they are minute in C. capistrata Luxton, 1987 ). Crotonia brisbanensis has slightly barbed lamellar setae, an elongate notogastral shield and the apophyses of setae h 2 are bifurcate and strongly diverging apically, whereas in C. capistrata the lamellar setae are smooth, the notogastral shield is broad and inflated and the apophyses of h 2 are much closer together and only slightly divergent apically.

Figures

FIGURE 3. Crotonia brisbanensis sp. nov. holotype female a) dorsal; b) ventral; c) posteriolateral.

FIGURE 18. Details of bothridia of a) Crotonia sterigma sp. nov.; b) Crotonia borbora Luxton, 1987; c) Crotonia brisbanensis sp. nov.; d) Crotonia maculata sp. nov.; e) Crotonia capistrata Luxton, 1987; f) Crotonia ardala Luxton, 1987; g) Crotonia monteithi sp. nov.; h) Crotonia daviesae sp. nov.; i) Crotonia weiri sp. nov.; j) Crotonia yeatesi sp. nov.; k) Crotonia cameroni sp. nov.; l) Crotonia eungella sp. nov. m) Crotonia queenslandiae sp. nov.; n) Crotonia seemani sp. nov.; o) Crotonia raveni sp. nov.