Rhynchoribates (Rhynchoribatodes) dynastes, Miko, Ladislav, 2016

Miko, Ladislav, 2016, Oribatid mites (Acarina, Oribatida) from French Guyana: review of the genus Rhynchoribates and description of three new species, Zootaxa 4061 (2), pp. 131-145 : 141-144

Rhynchoribates (Rhynchoribatodes) dynastes n. sp.

( Figs 5 , 6 )

Material. Holotype (female) and four paratypes (2 females, 2 gender unknown), French Guyana, Parc Amazonien Guyane Saul, Boucle de Monts La Fumée, near confluence of Crique Cochon and Crique quee Hocco (3°37´66´´N, 53°12´00´´W), 150 m above sea level (sample Nr. LM-2012-001). Mosses on trees, rotting wood, dead leaves on/ under fallen tree, in tropical rainforest. Collected by author, 2.III.2012.

The holotype and 2 paratypes are deposited in arachnological collection of National Museum of Prague, Czech Republic, 2 paratypes in the collection of the author.

Diagnosis. Medium sized Rhynchoribates with elongated, distally sharply pointed and laterally dentated rostrum. Prodorsum with net-like pattern of cuticular ridges and well developed sub-circular lamellar knob. All prodorsal setae including sensillus setiform, distally attenuated and pointed. Interlamellar setae long, rostral setae slightly bent and oriented anteriad. Notogaster with humeral processes and well developed cristae. Notogastral setae simple setiform, medium sized. Epimeral area with sclerotised formations and pair of oval porose areas. Setae ad1 and ag larger and longer than rest of ventral setae. Legs with some modified sabre-like ventral and lateral setae on femora, genua and tarsi. Proral setae of all legs thorn-like.

Description. Average body length 694 (holotype 650, range 650–730), average maximum width (notogaster in its mid-length) 406 (holotype 385, range 385–422). Further measurements are given for depicted paratype: ventral length 650, prodorsum length 331, maximum prodorsum width 240. Colour dark reddish brown. Whole body covered by layer of cerotegument, mostly fine granular and amorphous, on medial part of prodorsum and laterally on podosoma with larger tubercles. Smaller, but also more distinct tubercles present on notogaster.

Prodorsum. ( Figs 5 A, 6A, B). Relatively broad, with pattern of net-like ridges. Pedotectum I distinct, strongly sclerotised at tip, but less protruding than in other species. Rostrum ( Fig. 6 B) elongated, with parallel sides, distally with sharply pointed, narrow central projection and 8 (7–9) distinct teeth on each side. Lamellar knob distinct, subcircular, with distinct tubercular projection anteriorly (well visible in lateral view, Fig. 6 A), connected with interbothridial sclerites and bothridia by curved ridges. Anterior to and below lamellar knob, transversal triangular sclerite present and another curved transversal ridge more anteriorly, projecting anteriad. From this projection anteriad, unpaired longitudinal ridge, sparsely covered by large tubercles of cerotegument, reaches rostral end beyond ro insertion. Interbothridial sclerites present around in insertions, each with short interbothridial ridge posteriad, connected with bothridia by another short ridges; ridges present on lateral parts of prodorsum with rows of large cerotegument tubercles. Bothridia well sclerotised, each postero-laterally with angled postbothridial projection. Prodorsal setae ( Fig. 6 C) distinct, all setiform, attenuated distally, with sharp tips. Rostral seta (ro) rather short (59), simple, curved, oriented anteriad. Setae le subequal in length to ro (67), inserted below frontal tubercle of lamellar knob and above transversal sclerite ( Fig. 6 A, C). Setae in long (108), inserted on interbothridial sclerite. Sensillus setiform, long (188), shaped as usual in Rhynchoribates , with short straight proximal part and long, strongly curved, attenuated distal part. Lateral parts of prodorsum and podosoma above discidium with areas covered by large tubercles of cerotegument, discidium relatively small, distance of tips of discidia shorter than width of notogaster.

Notogaster. ( Figs 5 A, 6A). Sub-circular in dorsal view, with straight anterior border, somewhat flattened in lateral view. With distinct humeral tubercles (sometimes doubled) and medially with well developed arched ridge and notogastral cristae. In lateral view, long ridge runs from humeral area to posterior part of notogaster ( Fig. 6 A), bearing scale-like projection that covers small, oval porose area (p.a., Fig, 6A). Notogastral setae normal setiform, smooth, medium long (59–78). All lyrifissures and opening of opistosomal gland present in usual positions.

Gnathosoma. ( Fig. 5 B). Strongly elongated, infracapitulum with relatively broad basal part. Setae m, a, h of about same length (lateral view!), even if in ventral view m appear longest. Palp setation 2–1–3–8. Mentotectum broad, well developed.

Epimeral region. ( Fig. 5 B). Laterally framed by arched ridges. In central part, with enantiophyses E2 and V strongly developed, each with anterior and posterior tubercles fused, creating “clasps” bridging over the apodeme 2 and over ventrosejugal furrow (ventral bridge, vb), and both with small and thin, scale-like blades laterally and axially. Enantiophyse V paraxially with elongated, curved posterior ridges, which frame distinct anterogenital area (ang, Fig. 5 B). Distinct pair of oval porose areas present behind clasp created by enantiophyse V. Epimeral setal formula 3–1–3–5, all epimeral setae simple setiform, smooth, mostly medium long (40–55), seta 4d usually the longest (67). Seta 1c inserted on pedotectum I, setae 4a–d creating group arranged in short oblique row, seta 4e not inserted on discidium, but more axially, near longitudinal circumpedal ridge framing laterally epimere IV (cpl, Fig 5 B). this ridge ends behind acetabulum IV by spiniform projection oriented laterad..

Anogenital region. ( Figs 5 B, 6A). Genital opening much smaller than anal opening, distance between them subequal to length of genital opening. Broad, arched anterogenital area present, framed anterolaterally by sclerotised ridges. Anal plates with rugged anterior and posterior edges paraxially. Preanal sclerite small, oval to subtriangular. Common set of setae present: 7 pairs genital, 1 aggenital, 2 anal and 3 adanal ( Fig. 6 A). Length of genital setae similar to epimeral ones (35–40), length of adanal setae ad2 and ad3 similar. Both anal setae very short (12), seta an1 inserted slightly anterior to the midlength of anal plates; ad1 and ag much larger than other ventral setae, widened proximally and almost twice longer than others (53–61). Lyrifissure iad adanal, close to and aligned with the anal opening.

Legs. ( Fig. 6 E–F). Leg setation details and homology given in Table 1 , setal formula as follows: leg I 1–5 – 2(1)–4(2)–20(2); leg II 1–5 –2(1)–4(1)–15; leg III 2–3 –1(1)–3(1)–15; leg IV 1–2 –2–3(1)–12. Leg setae medium long, mostly setiform, smooth. Some lateral and ventral setae (mostly on tibia, Fig. 6 E, F) widened, not attenuated (sabre-form), almost straight, blunt. Trochanteral setae I and II inserted on a prolonged apophyse, rather fine and long (76). Proral setae of all legs modified: on legs I with thickened basal part, distally attenuated, thorn-like, on legs II–IV broad lancetiform, blade-like. Solenidia rather long, setiform or ceratiform, j1 longest, longer than any tibial seta. Famulus emergent, simple setiform, quite long.

Remarks. The new species is type of the newly defined subgenus Rhynchoribatodes (for detailed characters see subgenus diagnosis above). From other species of the subgenus, R. (R.) dilatatus is probably the nearest, having similar polygonal ridge structure and lamellar knob on prodorsum, similarly developed and inserted setae ro, similar shape and size of pedotecta I, anterior border of notogaster with humeral processes, cristae etc. Still, it clearly differs by several characters. Most striking is difference in shape of setae in and notogastral setae, which are club shaped, blunt and distally expanded (spatulate). Number of teeth on the rostrum is lower (5) compared to the new species. Ventral characters of R. (R.) dilatatus are unknown. Other two species— R. (R.) brasiliensis and R. (R.) ecuadoriensis —do not have fully developed ridges on prodorsum (they are absent or indistinct proximally), lamellar knob is differently developed or absent. Both species differ also by bacilliform, distally obtuse and not attenuated notogastral setae. Setae in of R. (R.) ecuadoriensis are significantly shorter than in new species, their length is only slightly exceeding that of le. Prodorsum of R. (R.) ecuadoriensis is much more densely covered by large tubercles of cerotegument, particularly in the areas around bothridia. Rostral teeth of this species are acute, positioned in transversal rows and oriented more anteriad. R. (R.) brasiliensis differs in addition also by clubshaped, obtuse seta in.

Derivatio nominis. The prodorsum of species in the lateral view resembles pronotum of some beetles from the family Dynastidae , therefore species name was selected to remind of this similarity.

Figures

FIGURE 5. Rhynchoribates (Rhynchoribatodes) dynastes n. sp., paratype. A—dorsal view; B—ventral view. Acronyms: ang — anterogenital area, cpl — circumpedal ridge, E 2 — enantiophyse E 2, tpf—tectum of podocephalic fossa, vb — ventral bridge created by merged tubercles of enantiophyse V. Scale bar: 200 µm.

FIGURE 6. Rhynchoribates (Rhynchoribatodes) dynastes n. sp. A—lateral view (notogastral setae not depicted); B—detail of rostrum in dorsal view; C—prodorsal and notogastral setae; D—detail of bothridium and sensillus; E—leg I; F—tibia and tarsus of leg IV. Acronym: p. a. — porose area. Scale bars: 200 µm (A), 50 µm (B – D), 100 µm (E – F).