Crotonia ramsayi, Colloff, Matthew J., 2015

Colloff, Matthew J., 2015, The Crotonia fauna of New Zealand revisited (Acari: Oribatida): taxonomy, phylogeny, ecological distribution and biogeography, Zootaxa 3947 (1), pp. 1-29 : 5-7

Crotonia ramsayi sp. nov.

( Figs. 1 , 2 a, 7a)

Dimensions. Holotype female length 1366 Μm, breadth 656 Μm; paratype females (n = 8) mean length 1387 Μm (range 1303–1449 Μm); mean breadth 712 Μm (range 600–782 Μm); paratype males (n = 8) mean length 1167 Μm (range 1130–1212 Μm), mean breadth 554 (range 498–581 Μm). Ratio of length of prodorsum to total length: 0.27 (holotype).

Female. Prodorsum: rostrum prominent, lateral edges incurved; rostral setae (ro) 30 Μm long, straight, spiniform, smooth ( Fig. 1 a). Lamellar setae (le) 248 Μm, recurved, smooth. Lamellar apophyses 79 Μm long, straight, tubular, more-or-less parallel, less than half as long as mutual distance; extending anteriorly as far as apices of rostral setae. Interlamellar apophyses twice as long as broad; interlamellar setae (in) 266 Μm long, slender, smooth, flagelliform, extending anteriorly just beyond apices of lamellar apophyses. Prodorsal ridges short (42 Μm), barely developed. Diameter of bothridium 46 Μm; anteriolateral auriculate ridge relatively narrow, with three blunt projections anteriorly, blunt lateral spine and posterior projection ( Fig. 7 a); hexagonal reticulations of operculum sparingly ornamented with well-developed ridges and with point of origin near lateral margin. Interbothridial ridge a faint shallow curve without median invagination. Median field of muscle sigilla present. Prodorsal microsculpture smooth, porose.

Notogaster: ratio of length to breadth 1.48; broadest between bases of setae cp and e 2 ( Fig. 1 a). Dorsosejugal suture simple, incomplete, with sparse tubercles. With 13 pairs of smooth notogastral setae. Pre-notogastral shield broader than notogastral shield, with rounded lateral margins; waisted at junction with notogastral shield, junction marked by transverse hyaline strip bearing long (441 Μm), flagelliform setae c 1 on well-developed tubercles. Apophyses of setae c 3 prominent, 33 Μm, at least twice as long as broad; setae c 3 flagelliform, 382 Μm long, recurved. Hysterosoma bulbous, inflated, lozenge-shaped. Notogastral shield elongated with slightly convex lateral margins, porose medially; bordered laterally by narrow strips of small tubercles extending posteriorly as far as lyrifissure ip. Lateral hyaline strip (suprapleural scissure) well developed, thin, bearing squat tubercles of setae cp, e 2 and f 2, extending posteriorly as far as lyrifissure ip. With narrow, porose strip lateral of hyaline strip bearing lyrifissure im, extending from posterior of seta cp to lyrifissure ip; lateral notogastral plates tuberculate. Setae cp, e 2 and f 2 short, curved, sub-equal in length (36–48 Μm). Setae d 2 short (37 Μm), thin, straight, setiform; bases 109 Μm apart. Opisthonotal gland opening gla positioned anterior of f 2. Caudal apophyseal cluster bilateral, not on medial stalk; apophyses of seta h 2 longest, parallel, directed posteriorly, apices slightly bulbous ( Fig. 2 a); caudal margin between them transverse. Apophysis of setae f 1 directed posteriodorsally, h 1 directed posteriorly; apophyses short, parallel, slightly bulbous, adjacent, emerging from caudal margin dorsal of apophyses of setae h 2. Apophyses of setae h 3 subequal to those of f 1 and h 1; anterior, ventral and lateral of them. Setae f 1 66 Μm long, flagelliform; h 1 42 Μm long, setiform; h 2 60 Μm long, spiniform, sparingly barbed; h 3 33 Μm long, setiform.

Venter: epimeres porose ( Fig. 1 b); epimeral setae except 4b smooth, thin, setiform, 27–36 Μm long; formula 3- 1-3-3; seta 4b longer than others (62 Μm), spiniform, 3c on well-developed tubercle. Genital plates sub-circular, posterior margin straight, posteriolateral margin straight, angled obtusely to posterior margin; each plate 217 Μm long, 121 Μm broad, with eight thin, setiform setae, 24–36 Μm long; two pairs of aggenital setae, subequal in length to genital setae. Anal plate 314 Μm long, 48 Μm broad, with three thin, setiform setae on central and posterior part of plate; three pairs of thin, setiform adanal setae. Ventral margin of notogaster surrounding anal plates V-shaped. Setae of p series smooth, thin, setiform, p 3 25 Μm, p 2 23 Μm, p 1 48 Μm, on short tubercles; setae p 1 separated by distance 3´width of their tubercles ( Fig. 1 b).

Type designation, material examined and locality data. Holotype female, eight paratype females, eight paratype males, Coprosoma cyanthoides litter, Dun Mountain Track, Nelson, 41°19'S 173°19'E, 610 m., coll. G.W. Ramsay, 7.iii.1972. Holotype and paratypes deposited in the New Zealand Arthropod Collection, Landcare Research, Auckland.

Etymology. This species is named in honour of its collector, Graeme W. Ramsay.

Remarks. Crotonia ramsayi sp. nov. can be differentiated from other members of the genus based on the following combination of characters: 1) the prominent naso; 2) the thin, parallel lamellar apophyses, extending beyond the rostral setae; 3) the bothridial ridge with several blunt projections; 4) the broad pre-notogastral shield, waisted at its junction with notogastral shield and separated by a transverse hyaline strip; 5) the two pairs of very long, smooth c setae; 6) the smooth lateral notogastral setae, sub-equal in length, 7) the relatively narrow notogastral plate, with marginal rows of tubercles and bounded by a thin hyaline strip with a broader strip laterally; 8) the bilateral caudal apophyseal cluster, joined basally, with smooth setae; 9) the apically bulbous apophysis of seta h 2; 10) the long spiniform epimeral seta 4b; 11) the eight pairs of thin genital setae.

Crotonia ramsayi sp. nov. is a member of the Unguifera species-group. It is morphologically most similar to C. unguifera (cf. below) with which it shares the prominent naso, the transverse hyaline strip separating the narrow notogastral shield from the broader pre-notogastral shield, waisted at the junction; the flagelliform c setae and the short, bilateral caudal apophyseal cluster. It differs in that the lamellar and caudal setae are smooth rather than barbed; the bothridial ridge is angled and with several blunt projections, rather than being rounded and crenellated; the lateral notogastral setae are sub-equal in length, rather than with cp considerably longer than the others and apophyses of setae f 1 are not joined to those of h 1, point posteriodorsally, are medial of those of h 2, rather than pointing dorsolaterally and positioned lateral of apophyses of h 2. The notogastral plate of C. ramsayi is narrow with convex margins, whereas in C. unguifera the margins are more-or-less parallel. Also, setae 4b of C. ramsayi are much longer and thicker than those of C. unguifera and the genital setae are thin and setiform, rather than thick and spiniform and setae p 1 are smooth and closer together.

Figures

FIGURE 1. Crotonia ramsayi sp. nov. holotype female; a) dorsal; b) ventral. Scale bar = 200 µm.

FIGURE 2. Lateral views of caudal clusters: a) Crotonia ramsayi sp. nov. paratype female; b) C. unguifera, female. Scale bar = 50 µm.

FIGURE 7. Details of bothridia of a) Crotonia ramsayi sp. nov.; b) Crotonia unguifera (Michael, 1908); c) Crotonia caudalis (Hammer, 1966); d) Crotonia brachyrostrum (Hammer, 1966); e) Crotonia cophinaria (Michael, 1908). Scale bars = 20 µm.