Trichoribates scilierensis, Bayartogtokh, B. & Schatz, H., 2008

Bayartogtokh, B. & Schatz, H., 2008, Trichoribates and Jugatala (Acari: Oribatida: Ceratozetidae) from the Central and Southern Alps, with notes on their distribution, Zootaxa 1948, pp. 1-35 : 2-9

Trichoribates scilierensis sp. nov.

(Figs. 1-3)

Trichoribates longipilis (part.): Schatz 1989, p. 120.

Latilamellobates cf. oxypterus : Fischer & Schatz 2007, p. 436.

Diagnosis. Rostrum broadly rounded in dorsal view, with a pair of minute lateral dens and a nose-like protuberance dorsally; rostral, lamellar and interlamellar setae barbed; lamella wide, with long and thin translamella; lamellar cusp with long lateral and medial dens; sensillus short, with elongate oval head; tutorium broad, with four or five small dentations at the dorso-distal end; 10 pairs of long and barbed notogastral setae; porose areas Aa large and round, A1 divided into two parts, A2 and A3 smaller, oval; all ventral setae barbed; epimeral setal formula 3-1-3-2; setae l" of tibiae and genua I, II very thick, much thicker than other setae; genu I with streng ventro-distal projection.

Measurements. Holotype: body length 532 µm, length of notogaster 446 µm, width of notogaster 364 µm; paratypes (n = 24): body length 494-562 (527) µm; length of notogaster 410-471 (460) µm; width of notogaster 338-387 (362) µm.

Integument. Body colour dark brown to yellowish brown. Surface of body and leg segments with thick cerotegument, roughened by small granules. Faintly microtuberculate on cuticle of prodorsum, notogaster, ventral plate, leg segments and subcapitular mentum. Microtubercles forming longitudinal Striae on femora III and IV.

Prodorsum (Figs. 1A, C, 2A-F, H-K). Rostrum broadly rounded in dorsal view, with a pair of minute lateral dens and with a nose-like protuberance dorsally (about 14-18 um elevated above prodorsal shield) (Figs. 1A, C, 2A-C, E). Rostral seta (ro) barbed, inserted laterally, underneath of ventro-distal end of tutorium, 72- 87 µm in length, extending beyond tip of rostrum, directed mediad. Lamella wide, with longitudinal striations, 112-127 µm in length, slightly converging, connected by moderately long and very thin translamella, slightly concave medially. Lamellar cusp with long lateral and medial dens subequal in length (10-18 µm), their size slightly variable, also depending on abrasion in old specimens (Figs. 1A, 2A, D-F, H). Lamellar seta (le) 91- 104 µm in length, ciliate, slightly thinner than rostral setae. Interlamellar seta (in) 99-150 µm in length, barbed, not reaching the anterior margin of rostrum, insertions concealed under anterior margin of notogaster. Sensillus short, exposed portion 43-48 µm in length, with squamose elongate oval head. Bothridium relatively small, irregularly funnel-shaped, almost completely covered by notogaster. Tutorium broad, 162-176 µm in length, with distinct cusp distally, bears four or five small dentations at the dorso-distal end (Figs. 1C, 2I-K).

Notogaster (Figs. 1A, C, D, 2G). Oval, about 1.3 x longer than wide. Anterior margin markedly arched anteriad; lenticulus present. Pteromorph well developed, curved ventrally. Ten pairs of notogastral setae present, ciliate, seta c longest (length 65-90 µm), other notogastral setae nearly equal in length. Porose area Aa largest (diameter 15-25 µm), almost round in shape; A1 divided into two parts, lateral area large, medial small (Figs. 1A, C, 2G). Porose areas A2 and A3 round to oval in shape, the latter slightly larger than the former. Lyrifissure im clearly visible in dorsal view, ia, ih and ips visible in lateral view, ip visible in posterior view, situated laterad A3. Opisthosomal gland opening (gla) located posterior to lyrifissure im.

Gnathosoma (Figs. 1B, 2L, M). Subcapitular mentum conspicuously wider than long. Hypostomal setae a, h and m distinctly barbed, length of a 20-22 µm, h, m 30-32 µm long. Chelicera with strongly sclerotized blunt teeth; setae cha and chb barbed, length 40-50 µm. Palp typical for family, palpal setation 0-2-1-3-10 including both ventral setae and solenidion omega of tarsus.

Epimeral region (Fig. 1B). Epimeral setae (except 1c) of medium length (15-20 µm), all finely barbed, seta 1c much longer (45-50 µm). Epimeral setal formula: 3-1-3-2, seta 4c not evident. Custodium reaching posterior margin of pedotectum II, discidium well developed, conspicuously projected laterally. Pedotectum I large, surface smooth, without striation.

Ano-genital region (Figs. 1B, D, 2N). Anal aperture larger than genital one, anal and genital plates smooth. All genito-anal setae of medium length, barbed (genital, aggenital setae 10-12 µm, anal setae 18-22 µm, adanal setae 22-25 µm in length); setal formula 6-1-2-3. Distance between bases of aggenital setae nearly equal to that between setae ad3-ad3. Seta ad3 situated in paranal position. Adanal lyrifissure iad short, situated at same level as setae an2, adjacent to anterolateral margin of anal aperture. Postanal porose area (Ap) narrowly elongate, longer than distance between bases of adanal setae ad2 (Fig. 1D).

Legs (Fig. 3). Lateral claws thinner than medial claw, claws of leg IV slightly longer and more slender than those of other legs. Tibia I with a relatively small, but distinct anterodorsal apophysis, bearing solenidion phi2. Solenidion phi1 on tibia I very long (115-140 µm), length of phi2 36-49 µm. Genu I with strong ventro-distal projection; femur and trochanter IV with distinct ventral keel or blade, distally rounded. Most leg setae distinctly barbed, except setae (p) and (u) on tarsi I-IV, and v on trochanter and femur IV Setae l" on tibiae and genua I, II very thick, much thicker than other setae, barbed. Formula of leg setation (including famulus): 1(1-5-3-4-20); II (1-5-3-4-15); III (2-2-1-3-15); IV (1-2-2-3-12); formula of solenidia: I (1-2-2); II (1-1-2); III (1-1-0); IV (0-1-0).

Material examined. Holotype: Italy, Provincia di Bolzano, Schlern/Sciliar massif, alpine meadows (46°30,56 ’ N, 11°33,92 ’ E, 2450 m a.s.l., 05 August 2007: female, leg. Irene Schatz). Paratypes: ibid., alpine meadow below rock face (46°30,68 ’ N, 11°35,31 ’ E, 2220 m a.s.l., 24 May 2007, leg. Irene Schatz: 2 males, 14 females), ibid. (01 July 2007: leg. H. Schatz). Type deposition: The alcohol preserved adult holotype and 2 adult paratypes will be deposited in: Muséum d'histoire naturelle, Genève, Switzerland, other specimens in Museo di Scienze Naturali Alto Adige, Bolzano, Italy, and in authors' collections.

Remarks. The new species is distinguishable from most other known species of Trichoribates by the long lateral and medial dens of the lamellar cusps. Moreover, in T. scilierensis the rostrum bears a nose-like protuberance, and porose area A1 is divided into two parts. Both characters are very rare in Trichoribates species. The division of porose area A1 is constantly observed in all examined specimens, although the shape and size of the two parts were slightly variable. The combination of these characters can be considered as a diagnostic feature of T. scilierensis sp. nov.

Trichoribates biarea Gjelstrup & Solhøy, 1994, described from Iceland, resembles the new species in some characters, namely in having large porose areas Aa, divided porose areas A1, long notogastral setae, and similar shape of the tutoria (our attempt was unsuccessful in getting the type specimens of T. biarea from the host museum for comparative study). However, according to the original description and figures (Gjelstrup & Solhøy 1994), in T. biarea the rostrum is concave without a nose-like protuberance, the medial dens on the lamellar cusps are minute, the translamella is considerably thicker, the head of sensilli are more swollen, the lamellar and interlamellar setae are much longer, and the epimeral and ano-genital setae are smooth. Gjelstrup and Solhøy (1994) described the species T. biarea from dry heat-lands and fell-fields in Iceland.

The new species is also morphologically similar to Trichoribates strigatus Mahunka & Mahunka Papp, 2006, described from Ticino and Appenzell, Switzerland (Mahunka & Mahunka Papp 2006), in having almost equal dens on lamellar cusps, long notogastral setae, dentate tutoria, and almost round and large porose areas Aa. Trichoribates strigatus is larger in body size (length 590-608 µm) than T. scilierensis , the rostrum of T. strigatus is irregularly undulate or serrate, the cuspidal dens are shorter, the head of sensilli are more swollen, the lamellar and interlamellar setae are much longer, the latter reach the anterior margin of the rostrum, and porose areas A1 are undivided.

The North American species, T. spatulasetosus Reeves, 1967, has equal sized lateral and medial dens of lamellar cusps, but, T. spatulasetosus differs from T scilierensis in the densely barbed and strongly swollen head of sensilli; the very long and thick lamellar and interlamellar setae; strongly concave anterior margin of translamella; undivided porose area A1, and a smaller body size (length of females 472-495 µm, males 443- 450 µm, according to Reeves 1967).

Trichoribates furcatus Schweizer, 1956, described from high alpine areas in the Swiss National Park, Grisons, Switzerland, resembles the new species by the presence of long dens on lamellar cusps, but in T. furcatus the lamellar cusps and the dens are extremely long, whereas the medial dens are longer than the lateral dens (Schweizer 1956). Also, in T. furcatus the interlamellar setae as well as the anterior notogastral setae are much longer than those in T. scilierensis . The body size of the Swiss species is larger (length 585-620 µm) than that of the new species.

Schweizer (1956) also provided a figure of T. oxypterus , described by Berlese (1910) from Italy. This species also has relatively long dens on the lamellar cusps as in T. scilierensis , but in T. oxypterus the lateral dens of the cusps are much larger than the medial ones, while in the new species the size of medial and lateral dens is equal. Moreover, the interlamellar setae in the species studied by Schweizer (1956) are much longer (extending beyond the tip of rostrum) than those of the new species.

It should be noted that T. oxypterus sensu Schweizer seems not to be the same species as T. oxypterus (Berlese, 1910). Mahunka and Mahunka-Papp (1995) examined the type specimens of T. oxypterus in the Berlese collection, giving a short diagnostic description and a figure of the prodorsum. The lateral dens of the lamellar cusps are very long, nearly as long as the basal part of cusps (much longer than that in Schweizer’s drawing), but the medial dens are absent; the lamellae and especially the translamella are much wider, the interlamellar and notogastral setae are relatively shorter, and the head of sensilli are shorter and more swollen compared to the clavate sensilli in Schweizer’s specimen. Shaldybina (1975) provided a figure of T. oxypterus , which is identical with that in the work of Schweizer (1956), but Mahunka and Mahunka-Papp (1995) noted that Shaldybina’s species is not identical with Berlese’s. Thus, it is obvious that Schweizer misidentified another species under the name of T. oxypterus . To clarify the status of T. oxypterus sensu Schweizer, the specimens in Schweizer’s collection will have to be studied.

Another problem is the validity of T. oxypterus . Subías (2004) listed T. oxypterus as a junior synonym of Viracochiella (Latilamellobates) incisella , described by Kramer (1897). According to the diagnostic characteristics and the figures given by Mahunka and Mahunka-Papp (1995), it is obvious that T. oxypterus is not a junior synonym of Kramer’s species. Therefore, we reject the synonymy by Subías (2004) and retain the validity of T. oxypterus .

Etymology. The name of the new species is derived from the term "Scilier", the name of the beautiful Schlern/Sciliar massif in the ladin language (Rhaeto-Romance), spoken by about 35000 people in the Dolomites area.

Distribution. Trichoribates scilierensis was found in large numbers in the Schlern/Sciliar area in the Southern Alps in subalpine and alpine meadows between 2200 and 2650 m a.s.l. (summit of Mount Petz) (Schatz 2008). The species was also found on Plattkofel/Sasso Piatto by Fischer and Schatz (2007) at 2200 m a.s.l., under the name “ Latilamellobates cf. oxypterus ”. This species was also recently recorded in Italy, Trentino, Mezzano: Lago Giarine southeast of the Schlern/Sciliar massif (2126 m a.s.l., 21 September 2005, leg. R. Gerecke: 1 ad.).

In material collected previously by one of us (H. S.) it became apparent that this species also occurs in other areas in the Central Alps: Austria, East Tyrol, Kalser Dorfertal - Daberklamm , with loose gravel and cushion plant vegetation (1520 m a.s.l., 17 July 1988, leg. H. Schatz, 6 ad.), sub Trichoribates longipilis (Schatz 1989) ; Austria, Tyrol, Ischgl - Idalpe , 2570 m a.s.l., in Caricetum curvulae (24 July 1991, leg. H. Schatz) .

By checking specimens from the collection of the Institute of Zoology, University of Innsbruck, we found two slides with Trichoribates scilierensis sp. nov., labeled as "slide 47: K. Schmölzer, Innsbruck near D8 leg. Janetschek ": 5 females, 4 males , and "slide 66 Schmölzer near D8 leg. Janetschek ": 8 females, 3 males . Unfortunately, we could not find records of these labels. Both Janetschek and Schmölzer collected in different parts of the Alps (e.g. Central Alps – Stubai and Zillertal mountains, Southern Alps – Dolomite mountains).

These records indicate that Trichoribates scilierensis sp. nov. seems to have a distribution in a wider area of the Central and Southern Alps, but it is restricted to high altitudes. The specimens from East Tyrol in the comparatively low Daberklamm (1520 m) were found in an isolated site with alpine pioneer vegetation (Schatz 1989).