Austronothrus rostralis, Colloff, Matthew J. & Cameron, Stephen L., 2014

Colloff, Matthew J. & Cameron, Stephen L., 2014, Beyond Moa’s Ark and Wallace’s Line: extralimital distribution of new species of Austronothrus (Acari, Oribatida, Crotoniidae) and the endemicity of the New Zealand oribatid mite fauna, Zootaxa 3780 (3), pp. 263-281 : 266-269

Austronothrus rostralis sp. nov.

( Figs. 2 , 3 b, 4)

Dimensions. Holotype female length 964 µm, breadth 585 µm. Paratype females mean length (n = 4) 978 µm (range 884–1074 µm, mean breadth 529 µm(range 465–585 µm). Paratype male lengths 803, 805, 773 µm, breadths 450, 422, 369 µm. Paratype tritonymphs (n = 4) mean length 852 µm (range 712–988 µm), mean breadth 407 µm (range 312–523 µm). Ratio of length of prodorsum to total body length: 0.34 (holotype).

Female. Prodorsum: rostrum acute; rostral setae 40 µm; straight, spiniform, pointing anteriorly, parallel, on closely-adjacent squat tubercles, giving rostrum bifurcate appearance. Lamellar seta recurved, smooth, 144 µm long, with flakes of cerotegument ( Fig. 2 a). Lamellar apophysis 75 µm long, 40 µm broad at base, distance between apophyses 1.5 × length. Interlamellar seta 207 µm long, slender, flagelliform, smooth, extending anteriorly as far as base of lamellar seta; on short tubercle twice as long as broad. Faint, parallel interlamellar ridges present. Diameter of bothridium 42 µm; anteriolateral auriculate ridge a long, thin, blunt, spine ( Fig. 3 b); hexagonal reticulations of operculum with linear series of small nodules along margins and ornamented with well-developed ridges. Prodorsal microsculpture smooth, porose.

Notogaster: mean ratio of length to breadth 1.26. Notogaster smooth; well-developed parallel centrodorsal ridges extending from dorsosejugal suture to caudal margin, diverging posterior of setae e 1 ( Fig. 2 a). Lateral suprapleural scissure narrow (17 µm), extending as far as seta f 2. Dorsosejugal suture relatively broad (27 µm), bearing apophyses of setae c 1-3, with curved projection pointing anteriorly between bases of setae c 1. Setae c 1-3 smooth, flagelliform apically, c 3 much longer (196 µm) than c 1 (144 µm); c 2 shortest (86 µm); on short tubercles. Distance between tubercles of c 3 and c 2, c 2 and c 1 sub-equal (66–75 µm) and between c 1 115 µm. Seta cp setiform, 75 µm. Setae d 1 and d 2 curved, setiform, sub-equal (98–115 µm long), longer than distance between them; e 1 much longer (184 µm); base of e 1 2 × further from base of d 2 than distance between d 1 and d 2. Seta e 2 curved, 132 µm long, f 2 127 µm; f 1 and h 1 flagelliform, sub-equal in length (109–125 µm). Caudal margin rounded; apophyses of h 2 projecting posteriorly; h 2 stout, curved, 121 µm long; h 3 167 µm long on short apophyses (29 µm), no longer than broad ( Fig. 2 c); caudal margin between them convex. Notogastral shield smooth, porose.

Subcapitulum: posterior part of mentum and lateral margin of gena punctate ( Fig. 2 b); seta h 22 µm long, m 9 µm, a 12 µm.

Venter: Epimeral plates smooth, porose ( Fig. 2 b). Epimeral setae variable in length (30–38 µm); formula 4-2-3- 2. Genital plate 190 µm long 115 µm broad; with seven pairs of genital setae, broad basally, tapering to fine point apically. Aggenital setae sub-equal in length to genital setae. Anal and adanal setae subequal (28–36 µm). Anal plate 49 µm broad anteriorly, 253 µm long. Seta p 1 196 µm long, flagelliform, smooth, on well-developed apophyses; setae p 2 and p 3 shorter (129 µm, 98 µm), thin, setiform. Caudal margin between apophyses of setae p 1 convex, pointed.

Legs: tarsi homotridactylous; lateral claws serrate along dorsal edge; median claw smooth.

Tritonymph. Prodorsum: rostral seta (ro) 23 µm long, straight, spiniform, smooth ( Fig. 4 a). Lamellar setae (le) 107 µm long, recurved, smooth. Lamellar apophyses almost as long as their mutual distance (56 µm); expanded laterally and basally, extending anteriorly almost as far as apices of rostral setae. Interlamellar setae (in) 153 µm long, flagelliform, smooth; extending anteriorly as far as apices of lamellar apophyses. Prodorsal ridges faint. Bothridium as in adult, with long, pointed projection extending anterolaterally. Prodorsal shield porose, surrounded by striate unsclerotised cuticle.

Gastronotic region: ratio of length to breadth 2.1; lateral margins parallel from seta c 3 to e 2 ( Fig. 4 a). Dorsosejugal suture discrete, transverse, with slight median projection. With 15 pairs of smooth notogastral setae including full complement of c, d and e series, positioned on porose sclerites, emerging from alveoli or short tubercles except c 3 and h 2 emerging from short apophyses. Seta c 3 the longest (186 µm), flagelliform; c 1 setiform, longer (56 µm) than c2 (32 µm), both on elongate porose sclerite. Seta d 1 60 µm long; d 2 93 µm; e 1 78 µm; distance from c 1 the same as to d 2; two-thirds that of distance from d 2 to e 1. Lateral setae setiform, cp 33 µm, e 2 74 µm, f 2 85 µm, f 1, 97 µm, h 1 116 µm. Setae h 2 stouter than others, curved, smooth, pointed, 107 µm long, on broad, conical apophyses. Notogaster with densely crenellated, folded cuticle medially and striate, unsclerotised cuticle laterally between porose sclerites.

Venter: epimeres porose, with median unsclerotised longitudinally striate integument, diverging laterally and becoming transverse posterior of genital plates ( Fig. 4 b). Epimeral setae smooth, spiniform, formula 4-2-3-3; setae 3c longer than others. Genital plates narrow, ovoid; each plate 85 µm long 30 µm broad with six setiform setae. Anal plate 260 µm long, 38 µm broad; three pairs of stout, setiform, adanal setae; subequal in length. Setae p 1 longest of the p series, then p 2 and p 3.

Material examined. Holotype female, ANIC 3505, trough of flight intercept trap, Filmy Fern Gully, Norfolk Island National Park, 29°0'.59"S, 167°56'58"E, ca. 180 m. Two paratype males, ANIC 3506, trough of flight intercept trap, Maurge Jowett’s [garden] (Red Road), Norfolk Island, 29°0'38"S, 167°56'44"E, ca. 250 m., coll. 1.ii.1985. Two paratype females, ANIC 3508, same data as ANIC 3506. Paratype male, ANIC 3510, trough of flight intercept trap, forest, Red Road Track, Norfolk Island National Park, 29°01'S, 167°57'E, ca. 180 m., coll. M. Sexton, 8.iii.1985. Two paratype females, ANIC 3511, same data as ANIC 3510. Types deposited in Australian National Insect Collection, CSIRO Ecosystem Sciences, Canberra.

Etymology. This species is named rostralis in reference to the characteristic shape of the rostrum and the rostral setae.

Remarks. Austronothrus rostralis can be distinguished from the other members of the genus by the following combination of characters: 1) with seven pairs of genital setae; 2) the anterior notogastral margin with a median curved projection; 3) with long, flagelliform setae p 1; 4) with seta e 1 almost twice the length of d 2 and d 1; 5) with seta h 2 about the same length as h 1 and f 1 and markedly shorter than e 2 and f 2; 6) the almost parallel rostral setae, positioned close together on short tubercles and pointing anteriorly; 7) the smooth, thick, flagelliform seta p 1, almost twice the length of p 2.

Austronothrus rostralis is morphologically similar to A. curviseta Colloff & Cameron, 2009 in relation to the lengths and disposition of the notogastral setae but the species differ in that the lamellar setae of A. rostralis are smooth rather than barbed and A. rostralis has seven, rather than eight, pairs of genital setae and much shorter setae cp, d 1 and d 2 than A. curviseta .

Figures

FIGURE 2. Austronothrus rostralis sp. nov. holotype female; a) dorsal; b) ventral.

FIGURE 3. Bothridia; a) Austronothrus kinabalu sp. nov.; b) Austronothrus rostralis sp. nov.