Crotonia unguifera ( Michael, 1908 )

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 : 8-10

Crotonia unguifera ( Michael, 1908)

( Figs. 2 b, 3, 7b)

Nothrus unguifera Michael, 1908 , p. 144, Pl. 19, Figs. 11 –15.

Acronothrus zealandicus Ramsay, 1958 , p. 76, Pl. 5, Figs. 1–10 nomen nudum. Crotonia unguifera ( Michael, 1908) :— Wallwork 1977b, p. 520, Figs. 8–9. Crotonia unguifera ( Michael, 1908) :— Luxton 1985, p. 30.

Crotonia unguifera ( Michael, 1908) :—Łochyńska 2008, p. 825.

Crotonia unguifera ( Michael, 1908) :— Colloff 2010b, p. 14.

Dimensions. Females: mean length (n = 6) 1697 Μm (range 1600–1817 Μm); mean breadth 913 Μm (range 820– 1024 Μm). Males: mean length (n = 13) 1371 Μm (range 1285–1496 Μm); mean breadth 736 Μm (range 653–805 Μm). Mean ratio of length of prodorsum to total length: 0.29.

Female. Prodorsum: rostrum prominent; rostral setae (ro) 53 Μm long, straight, spiniform, smooth ( Fig. 3 a). Lamellar seta (le) 219 Μm, recurved, sparingly barbed. Lamellar apophysis 120 Μm long, straight, tubular, more-orless parallel, almost as long as mutual distance; extending anteriorly as far as apices of rostral setae. Interlamellar apophysis twice as long as broad; interlamellar setae (in) 418 Μm long, slender, sparingly barbed or smooth, flagelliform, extending anteriorly beyond apex of curve of lamellar setae. Prodorsal ridges not apparent. Diameter of bothridium 55 Μm; anteriolateral auriculate ridge broadly convex, irregular, with a median fovea and crenellated ridges ( Fig. 7 b); hexagonal reticulations of operculum sparingly ornamented with well-developed ridges and with point of origin near lateral margin. Inter-bothridial ridge and median field of muscle sigilla not apparent. Prodorsal microsculpture smooth, porose.

Notogaster: ratio of length to breadth 1.35; broadest at level of bases of setae e 2 ( Fig. 3 a). With 13 pairs of notogastral setae; lateral ones smooth, caudal ones barbed. Dorsosejugal suture simple, slightly convex, complete. Pre-notogastral shield broader than notogastral shield, with rounded lateral margins; waisted at junction with notogastral shield marked by transverse hyaline strip bearing apically-flagelliform seta c 1 (113 Μm long) on welldeveloped tubercles. Apophyses of setae c 3 prominent, 40 Μm long, at least twice as long as broad; setae c 3 flagelliform, 485 Μm long, recurved. Hysterosoma bulbous, inflated, lozenge-shaped. Notogastral shield elongated with margins more-or-less parallel, with minute foveolae medially; bordered laterally by narrow strip of small tubercles extending posteriorly as far as lyrifissure ip. Lateral hyaline strip (suprapleural scissure) narrow, bearing squat tubercles of setae cp, e 2 and f 2, extending posteriorly beyond 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 porose. Setae e 2 and f 2 short, curved, sub-equal in length (53–60 Μm); seta cp much longer (120 Μm). Setae d 2 very short (33 Μm), curved, setiform; bases 106 Μm apart. Opisthonotal gland opening gla positioned just anterior of f 2. Caudal apophyseal cluster bilateral, not on medial stalk ( Fig. 2 b); apophysis of seta h 2 slightly longer than others, parallel, directed posteriorly, slightly waisted; caudal margin between them convex. Apophysis of seta f 1 short, directed vertically ( Fig. 2 b); base of apophysis of seta h 1 fused with lateral surface of apophysis of seta f 1, sub-equal in length, slightly bulbous basally, directed posteriolaterally, emerging from caudal margin dorsal and lateral of apophyses of setae h 2. Apophyses of setae h 3 slightly shorter than others, positioned ventral and lateral of them. All caudal setae barbed; f 1 83 Μm long, setiform; h 1 83 Μm, h 2 50 Μm, h 3 66 Μm.

Venter: epimeres porose ( Fig. 3 b); epimeral setae smooth, thick, spiniform, 33–46 Μm long; formula 3-1-3-3; seta 3a and 4b sub-equal in length, slightly longer than others (60 Μm); 3c on well-developed tubercle. Genital plates sub-circular, posterior margin straight posteriolateral margin straight, angled obtusely to posterior margin; each plate 305 Μm long, 153 Μm broad, with eight thick, setiform setae, 43–54 Μm long; two pairs of aggenital setae, shorter than genital setae. Anal plate 412 Μm long, 63 Μm broad, with three thick, setiform setae on central and posterior part of plate; three pairs of thick, setiform adanal setae. Ventral margin of notogaster surrounding anal plates U-shaped. Setae p 2-3 smooth, curved, setiform, 47 Μm long, p 1 barbed, 66 Μm long, on short tubercles, separated by distance 6 × width of their tubercles ( Fig. 3 b).

Material Examined and Locality Data. four females, 13 males, salt meadow, North Brother Island, Cook Strait, 41°7'S, 174°27' E, 10 m., coll. G.W. Ramsay, 12–19.v.1956. Three females, three males, Chionchloa sp., beating [foliage], Dun Mountain Track, Nelson, 41°19'S 173°24'E, 610 m., coll. G.W. Ramsay, 7.iii.1972. Soil site, Wharekaka [Martinborough], Wairarapa, 41°13'S 175°28'E, 20 m., coll. M. Luxton, 22.iv.1965. Twelve adults, beating, Kelceys [Kelsey’s] Bush, Waimate, 44°45'S 171°0'E, 175 m., coll. G.W. Ramsay, 20.i.1966.

Remarks. Crotonia unguifera can be differentiated from other members of the genus based on the following combination of characters: 1) the sparingly barbed c series setae; 2) setae cp are twice the length of setae e 2 and f 2; 3) the lateral margins of the notogastral plate have a line of tubercles; 4) the suprapleural scissure extending posteriorly to a point between lyrifissure ip and caudal apophyses; 5) the barbed caudal setae on bilateral apophyses arising from hysterosoma, not on a caudal stalk; 6) the caudal apophyses of seta h 1 emerging laterally from dorsally-directed apophysis of seta f 1; 7) setae p 2–3 are smooth, p 1 is barbed; 8) the aggenital region is tuberculate; 9) epimeral setae 3a and 4b are longer than the other epimeral setae.

Crotonia unguifera is most closely related to C. ramsayi sp. nov. (cf. Remarks for that species above). Wallwork (1977b) designated a lectotype of Crotonia unguifera and redescribed the species. Michael’s (1908) description contains no figures. Wallwork (1977b) commented on the limitations of his redescription due to the poor optical properties of Michael’s preparations: “The use of Balsam mountant prevents the clear definition of many of the body setae which are pale in colour, in any case. The raised cover slip does not permit the use of oil immersion.” Consequently, Wallwork (1977b; his Fig. 8) illustrated the prodorsal setae much shorter than they really are, and setae le as smooth rather than barbed. The lectotype has lost both setae cp and most setae from the caudal apophyses and the right notogastral margin. The gender of the lectotype was not specified, but its length (1391 Μm) falls within the range of the male specimens in the present study. Despite Wallwork’s caution, Łochyńska (2008) used the artefactually short setae le and in to differentiate C. unguifera from C. longisetosa Łochyńska, 2008 . However, setae d 2, e 2 and f 2 of the latter species appear to be longer than those of C. unguifera illustrated herein. Both species have barbed caudal setae.

Michael (1908) recorded C. unguifera from ‘Fielding’ [Feilding] and ‘Maunga Karetu’ [Maungakaretu], based on material he received from Edwin Bostock. Colloff & Cameron (2009) gave details of the origin and localities of Michael’s (1908) oribatid material (cf. also Baker & Colloff 2006), including mention that Bostock’s samples also included four adults of Holonothrus pulcher Hammer, 1966 , labelled “Maunga Karetu [Whangaehu Valley], NZ. J.W.B. Collection 4.2.92 ”.

Ramsay (1958) included a manuscript description of “ Acronothrus zealandicus sp. nov. ” from The Brothers island group, Cook Strait (cf. also Ramsay 1962), but the species was never published and the name is unavailable. An examination of Ramsay’s description indicates his species is without doubt Crotonia unguifera . The elongated setae cp, the morphology of the caudal apophyses and the barbed caudal setae are identical to those in the present supplementary description.

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 3. Crotonia unguifera (Michael, 1908), female; a) dorsal; b) ventral. Scale bar = 200 µm.

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

FIGURE 5. Crotonia brachyrostrum (Hammer, 1966), female; a) dorsal; b) ventral. Scale bar = 200 µm.

FIGURE 6. Crotonia cophinaria (Michael, 1908), 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.

FIGURE 9. Distribution of Crotonia spp. in New Zealand, based on records in Appendix 1. Crotonia obtecta and C. ramsayi sp. nov. are represented by single records and not mapped, nor is C. brevicornuta, recorded only from Campbell Island. Dashed line = Alpine Fault.

FIGURE 10. Environmental envelopes of all records of New Zealand Crotonia (a – c) and its major species groups (d – f). Note range of values on axes differs between (a – c) and (d – f).

FIGURE 11. Relationship between annual water deficit and vapour pressure deficit for all locality records of New Zealand Crotonia in relation to the main types of vegetation community.