Rhinoppioides quadrituberculatus MIKO, 2012

Miko, Ladislav, Mourek, Jan, Meleg, Ioana N. & Moldovan, Oana T., 2012, Oribatid Mite Fossils From Quaternary And Pre-Quaternary Sediments In Slovenian Caves I. Two New Genera And Two New Species Of The Family Oppiidae From The Early Pleistocene, Acta Musei Nationalis Pragae Series B 68 (1 - 2), pp. 23-34 : 24-28

Rhinoppioides quadrituberculatus MIKO sp. nov.

D i a g n o s i s: Rhinoppioides with broad, vaguely tripartite rostrum, four similarly developed tubercles on posterior part of prodorsum (postbothridial and interbothridial pairs). Prodorsum without lamellar or costular structures; sensillus simple, long, unbranched, smooth or with few minute barbs. Pair of variably developed, spiniform tubercles Va present in ventrosejugal area.

M e a s u r e m e n t s: Body length of holotype 375 Μm, maximum body width (notogaster) 218 Μm, dorsal length of prodorsum 139 Μm, width between the tips of pedotectum I 137 Μm. Measurements of two other studied individuals (paratypes, see Pl. 1D, F): body length 340 and 355 Μm, length of prodorsum 124 and 127 Μm, maximum width of body 196 and 188 Μm, width of prodorsum 126 and 135 Μm. Sensillus length from 100 to 125 Μm.

G e n e r a l c h a r a c t e r s: Available material with cuticle partly macerated (Pl. 1E, Pl. 2B); incomplete and damaged, not always enabling full assessment of characters. Body reddish-brown, in one case light brownish-yellow. Prodorsum finely punctate, finer punctation observable also on some areas ventrally ( Text-figs 1A, B ). Lateral parts of body around acetabula, in postbothridial and ventrosejugal area and in lateral parts of epimeres, with distinct fine granulation. Notogaster seemingly without particular miscrosculpture, smooth.

P r o d o r s u m: ( Text-fig. 1A , Pl. 2A). Prodorsum of oppioid form: conical, with broad rostrum. Rostral tectum ( Text-figs 2A , 1A, C ) relatively short, vaguely divided into three blunt, rounded lobes, separated by very shallow incisions; lateral lobes as broad as or broader than central lobe, and projecting slightly more anteriad. Pedotectum I well developed and quite strong; pedotectum II weakly developed, usually present in rudimentary, but observable form ( Text-fig. 2C , Pl. 2D); in dorsal view appearing as pointed projection lateral to bothridia. Prodorsum without lamellae, costulae or analogous structures and without furrows, in lateral view ( Text-fig. 1C ) arched. Postbothridial tubercles merged with posterior part of bothridia (as in Oppiella sensu lato), creating a distinct postbothridial projection. Interbothridial tubercles simple but well developed, of a size and shape similar to postbothridial tubercles ( Text-fig. 1A , Pls 2A, B). Lateral tecta ( Text-fig. 1A : lt) in sejugal area well developed, granulated. Only one prodorsal (lamellar) seta preserved in one individual, relatively long (29 Μm), setiform, smooth. Insertions of rostral setae close to the anterior rostral margin, located on more sclerotized transversal band behind rostral tectum, sometimes even on indistinct tubercles. Insertions of rostral, lamellar and interlamellar setal pairs all situated at similar mutual distances, collectively outlining a long rectangle. Distance ro -le as long as le -in or slightly longer. Insertions of exobothridial setae present laterally and more ventrally to bothridia, on usually distinct tubercle, with a small pore anterior to them. Sensillus of very characteristic form: long (100, 107 and 125 Μm), setiform or very slightly spatulate distally, narrowed but blunt at end, smooth, without cilia or branches but sometimes with two or three small, indistinct barbs or spines ( Text-fig. 1C , Pl. 2A).

N o t o g a s t e r: ( Text-fig. 1A , Pl. 1). Difficult to observe in detail on holotype, absent from one paratype (Pl. 1F), and highly damaged in the other one. Shape of notogaster broadly oval to ovoid, with short notogastral crista present ( Text-figs 1A , 2D , Pl. 2B), projecting slightly anteriad as small, but visible humeral angle. Anterior margin of notogaster between humeral angles almost straight. Insertions of notogastral setae not distinguishable in available material.

V e n t r a l c h a r a c t e r s: ( Text-fig. 1B , Pls 2 E-F). Surface of ventral plate at least in some parts finely punctate, with muscle sigillae visible mostly on epimeres III and IV. Tectum of podocephalic fossa with distinct spiniform apophysis ( Text-fig. 2C , 1 B-C, Pl. 2C), sometimes less visible or slightly reduced. Sejugal epimeres with a pair of sharp, posteriad projecting, spiniform tubercles Va, adjacent to ventral surface and in some individuals less developed or partly reduced ( Text-figs 1B , 2E ). A pair of smaller and less distinct, blunt tubercular structures also observed on epimeres 2, although it is not clear if they were really projecting above the surrounding surface or only created by local internal thickening of cuticle (E2a in Text-fig. 2E ). Genital opening rather small, about two times shorter and narrower than anal opening; genital and anal plates missing in available material. Short and simple preanal sclerite present, relatively tall (thick) when seen in lateral view ( Text-fig. 1C ). Posterior end of ventral plate in postanal area thickened ( Text-fig. 1C ), axial part in ventral or dorsal view slightly invaginated ( Text-figs 1A, B ). No ventral setae preserved, except perhaps single epimaral seta 1c in one of the paratypes – although hardly observable, appearing as relatively short and smooth ( Text-fig. 1C , under pedotectum I); epimeral formula (I to IV) most probably as usually seen in Oppiidae (3-1-3-3), but lateral areas difficult to observe and setal insertions (eg. 3c, but possibly 4d) may be misinterpreted or overlooked ( Text-fig. 1B , Pl. 2F). Single aggenital and three adanal setal pairs in usual positions. Discidium ( Text-fig. 1B , Pl. 2E) normally developed, tooth-like or triangular, blunt.

L e g s: ( Text-fig. 3 ). No complete legs were present in our material. Except for one of the paratypes, trochanters III and IV were preserved ( Text-fig. 1C ). However, two of the studied individuals (holotype, and one paratype which was later lost in the course of the study) contained parts of legs inside the body cavity. Forms and size of segments resembles those of oppioid mites, but it can only be speculated if the leg parts actually belonged to the studied individuals ( Text-figs 3 Aa, Ab and B). In any case, most probably all types of segments were present, indicating that these legs were most probably not, or not significantly, longer than the measured body of R. quadrituberculatus n.sp. If the leg segments belong to the same individual, and their speculative identification as presented in Text-fig. 3 below is (at least partly) correct, then the length of the first pair of legs could be estimated as less than 295 Μm (assuming that tarsus I should be shorter than tarsus IV), and the length of assumed leg IV could be around 375 Μm.

M a t e r i a l e x a m i n e d: Holotype (Pls 1 A-C, sampling label “mite 007-2”) and three paratypes (Pl. 1D, sampling label “mite 007-1”; Pl. 1 E, sampling label “mite 007-7”; and Pl. 1 F, sampling label “mite 007-3”) were present in material from the same sample ( R4 ) from red clay Pleistocene sediments, about 1.8 million years old, collected from a profile of clastic sediments from the cave Račiška pečina in the Classical Karst ( Kras ), Slovenia. One of the individuals (007-1) was unfortunately lost after examination. The holotype (mounted in Canada balsam) is deposited in the Acarological Collection of Senckenberg Museum Goerlitz , one mounted paratype is deposited in the Emil Racovita Institute of Speleology in Cluj-Napoca, Romania, and one paratype is in the collection of the National Museum in Prague.

D e r i v a t i o n o m i n i s: The name of genus reflects the similarity to Rhinoppia, a subgenus of Oppiella , characterized by an elongated rostrum and absence of lamellar costulae and well developed tubercules. The species name relates to the characteristic set of four similarly developed tubercles on the posterior part of the prodorsum.

R e m a r k s: This species was reported in Moldovan et al. (2011) as Oppiella (cf. Rhinoppia) sp. 1 in Text-fig. 3f and as Oppiella (Rhinoppia) sp. 2 in Pl. 1.

Figures

Text-fig. 1. Rhinoppioides quadrituberculatus MIKO gen. et sp. nov. A – dorsal view of holotype (prodorsal setae largely missing except right lamellar seta, notogastral setae missing and their insertions not discernable); B – ventral view of holotype (genital and anal valves missing, only insertions of ventral setae visible, gnathosoma missing); C – lateral view of paratype (notogaster missing). Bar indicates 100 µm. For explanation of acronyms see page 31.

Text-fig. 2. Rhinoppioides quadrituberculatus MIKO gen. et sp. nov. A – rostrum; B – variation of sensillus; C – ventral view on lateral part of epimeral region; D – laterodorsal view on bothridial and sejugal area; E – ventral spines Va (drawing and micrograph of the part of ventral plate of paratype). Bars indicating 50 µm. For explanation of acronyms see page 31.

Text-fig. 3. Rhinoppioides quadrituberculatus MIKO gen. et sp. nov. Above: assumed fragments of legs as seen in body cavity of holotype (Aa – in dorsal view, Ab – in ventral view) and paratype (B, only dorsal view available). Below: speculative reconstruction of legs, assumed segments leg IV in above rows (numbers 1, 3, 5, 7, 12, 13, 14), assumed segments of leg I below (numbers 6, 9, 10). Rest of the segments assumed to belong to legs II and III. Only trochanters III (nr. 8) and IV (nr. 7, 12) undoubtedly belonging to the new species. Bars indicating 50 µm, numbers indicate identity of segments.