Crotonia caudalis ( Hammer, 1966 )

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 : 10-12

Crotonia caudalis ( Hammer, 1966)

( Figs. 4 , 7 c)

Acronothrus caudalis Hammer, 1966 , p. 33, Fig. 40.

Crotonia caudalis ( Hammer, 1966) :— Luxton 1982, p. 255, Figs. 7–9 . Crotonia caudalis ( Hammer, 1966) :— Luxton 1985, p. 30.

Dimensions. Females: mean length (n = 5) 1841 Μm (range 1792–1895 Μm); mean breadth 1018 Μm (range 922– 1069 Μm). Males: mean length (n = 3) 1536 Μm (range 1472–1575 Μm); mean breadth 802 Μm (range 742–896 Μm). Mean ratio of length of prodorsum to total length: 0.31

Female. Prodorsum: rostrum prominent; rostral setae (ro) 47 Μm long, straight, spiniform, smooth ( Fig. 4 a). Lamellar setae (le) 304 Μm, recurved, smooth. Lamellar apophyses 140 Μm long, straight, tubular, divergent, as long as mutual distance; extending as far as apices of rostral setae. Interlamellar apophyses twice as long as broad; interlamellar setae (in) 425 Μm long, slender, smooth, flagelliform, extending as far as curve of lamellar setae. Prodorsal ridges short (101 Μm). Diameter of bothridium 54 Μm; anteriolateral auriculate ridge broad, U-shaped, with a series of fine, blunt spine-like structures laterally, with an anterior fovea ( Fig. 7 c); hexagonal reticulations of operculum sparingly ornamented with fine ridges and with point of origin near anterior margin. Inter-bothridial ridge faint, marked by diffuse line of tubercles; median field of muscle sigilla well-developed. Prodorsal microsculpture smooth, porose.

Notogaster: ratio of length to breadth 1.28; broadest at level of bases of setae e 2 ( Fig. 4 a). With 13 pairs of notogastral setae; lateral ones smooth, caudal ones barbed. Dorsosejugal suture simple, slightly convex, complete. Pre-notogastral shield with rounded lateral margins, waisted posterior of setae c 3, fused with notogastral shield: transverse hyaline strip absent. Seta c 1 460 Μm long, on well-developed apophyses, flagelliform, smooth, extending almost to bases of lamellar apophyses. Seta c 3 273 Μm long, extending only as far as bothridia. Hysterosoma bulbous, inflated, lozenge-shaped. Notogastral shield fused with lateral notogastral plates: lateral hyaline strip (suprapleural scissure) absent. Notogastral shield with sparse tubercles anterior of setae cp, otherwise smooth; margins of shield marked by narrow strip of small tubercles extending posteriorly as far as seta f 2 and anteriorly as far as seta cp. Lateral setae and lyrifissures im and ip positioned on broad, smooth strip of cuticle bordered laterally by an additional narrow strip of tubercles. Seta cp flagelliform, 172 Μm long, reflexed; f 2 and e 2 shorter than cp, sub-equal in length (102–140 Μm). Seta d 2 very long (320 Μm), flagelliform, setiform; on short tubercles 98 Μm apart. Opisthonotal gland opening gla positioned anterior of f 2. Caudal apophyseal cluster bilateral, but close together (55 Μm apart) on projecting medial stalk. Apophysis of seta h 2 longer than others (62 Μm), parallel, directed posteriorly; caudal margin between them transverse. Apophysis of seta f 1 short, subequal in length to those of h 1 and h 3 (31–43 Μm), directed posteriolaterally. Apophysis of seta h 1 directed posteriorly, base fused with dorsal surface of apophysis of seta h 2. Apophysis of seta h 3 ventral of others, directed posteriolaterally. All caudal setae barbed; f 1, h 1 and h 3 sub-equal in length (70–94 Μm), seta h 2 slightly longer than others (106 Μm).

Venter: epimeres porose, sparingly tuberculate along anterior margins ( Fig. 4 b); epimeral setae smooth, thick, spiniform, 47–59 Μm long; formula 3-1-3-3; seta 4b no longer than others; 3c on well-developed tubercle. Genital plates sub-circular, posterior margin straight posteriolateral margin straight, angled obtusely to posterior margin; each plate 281 Μm long, 133 Μm broad, with eight thick, setiform setae, 39–62 Μm long; two pairs of aggenital setae, as long as genital setae. Anal plate 398 Μm long, 70 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 U-shaped. Setae of p series smooth, curved, setiform; p 1 longer (62 Μm) and thicker than others, on short tubercles, separated by distance 3 × width of their tubercles ( Fig. 4 b).

Material Examined and Locality Data. Three females, one male, litter of Olearia colensoi, Mount Wharite Ridge. 40°15'S 175°51'E, 885 m, coll. A.V. Spain, 29.x.1966. Two males, two females, Tahurangi Hut, Mount Taranaki [Mt. Egmont], Taranaki. 39°14'S 175° 33'E, 1524 m., coll. J.E. Woodward, 14.xi.1951. Two males, soil site, Wharekaka [Martinborough], Wairarapa. 41°13'S 175°28'E, 20 m., coll. M. Luxton, 22.iv.1965.

Remarks. Crotonia caudalis can be differentiated from other members of the genus based on the following combination of characters: 1) the fusion of the pre-notogastral and notogastral plate, marked by the absence of a transverse anterior hyaline strip; 2) the fusion of the notogastral shield and the lateral notogastral plates, marked by the absence of longitudinal hyaline strips; 3) the extremely long setae d 2; 4) the long, flagelliform c series setae with c 1 longer than c 3; 5) the bifurcate caudal cluster on a short stalk; 6) the smooth lateral notogastral setae and barbed caudal setae; 7) the two longitudinal rows of tubercles on the dorsum, the median pair marking the position of the margins of the fused notogastral shield and the lateral pair separated from the medial pair by a broad smooth strip of cuticle.

Crotonia caudalis is morphologically most similar to C. longibulba Luxton, 1982 from New Zealand. Both species have the caudal apophyseal cluster on a prominent stalk but in C. longibulba the apophyses of setae h 2 are elongated and inflated apically whereas in C. caudalis they are not.

The description of Hammer (1966) has slightly shorter setae c 3 and d 2 than the specimens examined herein. Hammer (1966) described the caudal setae as smooth, though Luxton (1982) illustrated them as barbed. This discrepancy is probably due to differences in microscopy and microtechnique between these two workers.

Figures

FIGURE 4. Crotonia caudalis (Hammer, 1966), female; a) dorsal; b) ventral. Scale bar = 200 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.