Crotonia utricularia, 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 : 9-15

Crotonia utricularia sp. nov.

( Figs. 5–7 , 8 c)

Dimensions: holotype female length 1536, breadth 832. Paratype male length 1406, breadth 664. Paratype deutonymph length 948, breadth 506. Paratype tritonymph lengths 1201, 1240, breadths 648, 616. Ratio of length of prodorsum to total body length: 0.38 (holotype).

Description of female. Prodorsum: ratio of length to breadth 1.07. Rostrum well-developed, with prominent naso, lateral edges incised; rostral seta 65, straight, spiniform, smooth, on short tubercle ( Fig. 5 a). Lamellar seta 320, recurved, smooth. Lamellar apophyses 162, straight, thin, cylindrical, parallel, three quarters as long as their mutual distance, extending anteriorly as far as bases of rostral setae. Interlamellar apophysis as long as broad; interlamellar seta slender, 342, smooth; extending anteriorly almost as far as apical curve of lamellar setae. Prodorsal ridges absent. Diameter of bothridium 46; lateral ridge of bothridium a narrow flat lobe, detached posteriorly and with a blunt anterior projection ( Fig. 8 c). Inter-bothridial ridge and median field of muscle sigilla very faint, barely visible. Prodorsal microsculpture smooth, porose.

Notogaster: ratio of length of notogaster to breadth of notogastral shield 3.13; notogastral shield broadest at level between bases of setae cp and e 2 ( Fig. 5 a); ratio of width of shield to entire notogastral width 0.38; lateral margins of opisthosoma inflated, sub-lozenge-shaped, widest lateral of bases of setae e 2, anteriolateral margins converging to just posterior of apophyses of setae c 3. Dorsosejugal suture a diffuse line level with bases of setae c 1 and c 3. Pre-notogastral shield absent. Anterior hyaline margins of notogastral shield abutting dorsosejugal suture between base of seta c 1 and c 3. Notogaster with 13 pairs of smooth setae. Those of c series long, slender, flagelliform; seta c 1 (470) on short, cylindrical apophysis; c 3 (380) on long, well-developed, anteriorly-directed, conical apophysis (36 long) at lateral margin of dorsosejugal suture. Distance between bases of c 1 about three quarters of that between c 1 and c 3. Lyrifissure ia located immediately posterior of apophysis of seta c 3. Notogastral shield narrow, smooth, porous, elongated, sides more-or-less parallel, slightly converging posteriorly; with narrow lateral hyaline strip (suprapleural scissure) bearing squat, welldeveloped tubercles of setae cp, e 2 and f 2. Broad strip of smooth, porous cuticle lateral of suprapleural scissure, with underlying transverse musculature, bearing lyrifissures im and ip, bounded laterally by thin, interrupted line of darker cuticle. Seta cp short, curved (84), d 2 short, straight, setiform (46). Opisthosomal gland opening gla positioned anterior of short (76), setiform seta f 2. Caudal apophyses in paired bilateral clusters originating directly from caudal margin: no caudal stalk present. Apophysis of f 1 curved dorsally (60); that of h 1 (55) projecting posteriorly; that of h 2 (80) directly ventral of h 1, projecting posteriorly. Caudal margin between apophyses of setae h 2 transverse, distance between apophyses of h 2 only slightly longer than their length. Flagelliform smooth setae f 1 and h 1 141 and 172. Seta h 2 53, spiniform, slightly barbed. Seta h 3 (65) and its apophysis positioned ventral of f 1 when viewed dorsally.

Ve n te r: epimeral microsculpture smooth, porose ( Fig. 5 b); epimeral setae smooth, spiniform, formula 3-1- 3-3; subequal (ca. 38–53); 1b, 1c and 3c each on well-developed tubercle. Lateroventral circumgastric scissure (lcs) narrow, straight, forming a slightly obtuse angle (ca. 130°) with narrow perianal circumgastric scissure (pcs). Anteriolateral margin of adanal plate at junction of lcs and pcs not indented. Genital plates subcircular; posterior margin transverse; posteriolateral margins straight, diverging. Perigenital region sparsely tuberculate. Each genital plate 258 long, 152 broad with eight spiniform setae, subequal in length (45–55); two pairs of aggenital setae, subequal in length to genital setae. Anal plate 68 broad, 342 long, with three short (45) setiform setae distributed along most of length of plate: not concentrated in posterior half. Three pairs of spiniform adanal setae, ad 2-3 slightly shorter and thinner than spiniform stout ad 1 (38); distance between ad 2 and ad 3 two thirds of that between ad 2 and ad 1. Ventral margin of notogaster surrounding anal plates V-shaped. Setae p 1 curved, short (61) on short tubercles, their mutual distance three times their length; p 2 48, setiform; p 3 45.

Gastronotic region: ratio of length to breadth 1.16; broadest at level of setae d 2 ( Fig. 6 a). Dorsosejugal suture marked by series of transverse striae. With 13 pairs of notogastral setae, all smooth. Apophyses of lateral setae prominent tubular extensions of ovoid porose sclerites. Seta c 1 347 long, on relatively long (30) cylindrical apophysis lacking porose sclerite basally. Distance between bases of setae c 1 slightly less than between those of c 1 and c 3. Seta d 2 28 long, on short tubercle. Apophyses of setae c 3 193 apart, those of cp, e 2 and f 2 positioned more medially, 94, 145 and 102 apart respectively. Lateral setae flagelliform, c 3 248, cp 353, e 2 116, f 2 276, f 1 364. Caudal apophyses in paired bilateral clusters directed posteriorly; apophysis of seta h 1 slightly longer than others; that of h 2 ventral and lateral of h 1; that of h 3 ventral and lateral of h 2. Caudal margin between apophyses of setae h 1 straight, transverse, 1.5 time length of apophysis of h 1. Seta h 1 198, h 2 202, h 3 170. Notogastral shield region demarcated by narrow, median longitudinal line of tubercles, lateral of which cuticle is longitudinally striate, lacking tubercles.

Deutonymph. Prodorsum: rostrum with well-developed naso; rostral seta (ro) 36 curved, smooth, emerging from short tubercle ( Fig. 6 a). Lamellar seta (le) 145 curved, smooth. Lamellar apophysis 83, slightly shorter than their mutual distance, extending anteriorly almost as far as apices of rostral setae. Interlamellar seta (in) 243, flagelliform, smooth, extending anteriorly almost as far as arc of lamellar setae. Prodorsal ridges absent. Lateral ridge of bothridium a narrow flat lobe, detached posteriorly and with a blunt anterior projection. Inter-bothridial ridge curved. Median field of muscle sigilla present. Prodorsum porose; region posterior of interbothridial ridge with striate unsclerotised cuticle.

Ve nt er: epimeres porose ( Fig. 6 b), with median, unsclerotised, longitudinally-striate integument diverging in perigenital region and becoming transverse. Epimeral setae smooth, spiniform, some with bacilliform cerotegument, formula 3-1-3-3; setae 3c longer than others, on well-developed tubercle. Genital plates elongate, ovoid; each plate 70 long 43 broad, with four spiniform setae with bacilliform cerotegument; one pair of aggenital setae, subequal in length to genital setae. Anal plate 153 long, 27 broad; three pairs of spiniform adanal setae; ad 1 slightly longer than others, on prominent tubercle. Setae of p series on sclerotised apophyses; seta p 2 67 long, p 3 54; p 1 longer (96), flagelliform apically, their apophyses broadly separate.

Tritonymph: Prodorsum: as for protonymph except as follows: rostral seta (ro) 35, lamellar seta (le) 306; lamellar apophyses 122, three quarters as long as their mutual distance; extending anteriorly well beyond apices of rostral setae ( Fig. 7 a). Interlamellar seta (in) 275, extending anteriorly almost as far as arc of lamellar setae. Lateral ridge of bothridium as in protonymph and adult. With deeply-curved inter-bothridial ridge. Median field of muscle sigilla present. Prodorsum porose; region posterior of interbothridial ridge with striate unsclerotised cuticle.

Gastronotic region: ratio of length to breadth 2.0. Notogaster with median longitudinal line of tubercles bordered laterally by parallel tuberculate ridges, lateral of which cuticle is longitudinally striate with sparse tubercles around which striae are curved ( Fig. 7 a). Caudal apophyses subequal in length; that of h 2 positioned medially and ventrally of that of h 1.

Ve nt er: genital plates elongate, ovoid; each plate 124 long 41 broad with six spiniform setae ( Fig. 7 b); two pairs of aggenital setae, subequal in length to genital setae. Anal plate 315 long, 60 broad; three pairs of spiniform subequal adanal setae, and three pairs of anal setae positioned on central region of plates.

Material examined. Holotype female, trough of flight intercept trap, forest, Red Road Track, Norfolk Island National Park, 29° 0'37.73"S, 167°56'43.49"E, ca. 250 m., coll. M. Sexton, 8.iii.1985 ( ANIC bulk sample no. 3510). Paratype male, trough of flight intercept trap, Filmy Fern Gully, Norfolk Island National Park, 29° 0'.60.00"S, 167°56'59.99"E, ca. 180 m ( ANIC bulk sample no. 3505). Paratype deutonymph, 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.iv.1985 ( ANIC bulk sample no. 3508). Two paratype tritonymphs, 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 ( ANIC bulk sample no. 3506). All types deposited in Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. The specific name, utricularia , is derived from the Latin, utriculus, meaning a little bag; alluding to the morphology of the hysterosoma.

Remarks. This species differs from all other Crotonia spp. by the following combination of characters: 1) the broad strip of smooth, porous cuticle lateral of the suprapleural scissure, bearing lyrifissures im and ip, bounded laterally by a thin, interrupted line of darker cuticle; 2) setae h 2 spiniform, short and barbed; 3) setae h 1 and f 1 smooth, flagelliform apically; 4) setae d 2 minute; 5) setae c 1 and c 3 long, flagelliform, extending anteriorly at least as far as apophyses of interlamellar setae, c 1 longer than c 3; 6) notogastral shield and pleuraspis smooth, porose; 7) the short lateral notogastral setae on well-developed tubercles, with cp and f 2 subequal, curved and e 2 half their length and setiform; 8) the mutual distance between tubercles of setae p 1 short, only 2–3 times that of length of tubercles; 9) the narrow, smooth, porous, elongated notogastral shield.

The association of the nymphs with the adult female of C. utricularia is based on the following shared characters: the narrow, parallel notogastral shield, represented in the nymphs by the narrow, median longitudinal line of tubercles; setae c 1 and c 3 long, flagelliform, extending anteriorly at least as far as apophyses of interlamellar setae, c 1 longer than c 3; setae e 2 the shortest of the lateral notogastral series; the relative lengths and configuration of the caudal apophysis and the transverse caudal margin between the parallel apophyses of setae h 2.

Crotonia utricularia is morphologically most similar to Crotonia unguifera ( Michael, 1908) from New Zealand, as redescribed by Wallwork, 1977a based on Michael’s (1908) three type specimens, all of which are mounted on microscope slides in dorsal aspect. This renders ventral characters difficult to see, and there is some doubt about the character states of the ventral setation, particularly the epimeral setal formula (3c is not included in Wallwork’s redescription) and the number of genital setae (each plate has ‘at least six’). Both species have the same shaped opisthosoma and notogastral shield and similar relative lengths and configuration of the caudal apophyses and their setae, though setae h 2 of C. unguifera are smooth, and f 1, h 1 and h 3 are missing from the types. The two species also share elongated, flagelliform setae c 1 and c 3, with c 1 the longest, as well as short lateral notogastral setae, though those of C. unguifera emerge from alveoli, not tubercles. Crotonia unguifera is shorter and thinner than C. utricularia , and the mutual distance of tubercles of setae p 1 of C. unguifera is at least twice as long as for the latter species. The notogastral shield and pleuraspis of C. utricularia is completely smooth and porose, whereas C. unguifera has a pair of lateral ridges and the cuticle between the ridge and the suprapleural scissure is tuberculate. There is also a further tuberculate ridge on the pleuraspis, lateral of the suprapleural scissure.

Crotonia utricularia was restricted to samples from remnant forest and adjacent areas around Mt. Pitt Reserve. It was absent from samples taken at Rocky Point Reserve, a relatively exposed coastal cliff location of herbaceous vegetation, Norfolk Island Pine ( Araucaria heterophylla ) and Lagunaria patersonia , which Holloway (1977) remarked was of relatively low plant diversity.

Figures

FIGURE 5. Crotonia utricularia sp. nov. holotype female a) dorsal; b) ventral.

FIGURE 6. Crotonia utricularia sp. nov. deutonymph a) dorsal; b) ventral.

FIGURE 7. Crotonia utricularia sp. nov. tritonymph a) dorsal; b) ventral.

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