Rhynchoribates danbartai, 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 : 135-138

Rhynchoribates (s. str.) danbartai n. sp.

( Figs 1 , 2 )

Material. Holotype (female) and one paratype (damaged fragment,?female), French Guyana, Montagne de Kaw, near Auberge Camp Caiman, close to reserve Coq du Roche (4°34´23´´N, 52°11´58´´W), 150 m above sea level (sample Nr. LM-2012-008). Litter, dead leaves and rotting wood on the soil surface in tropical rainforest. Collected by author, 10.III.2012.

The holotype is deposited in arachnological collection of National Museum of Prague, Czech Republic, paratype in the collection of the author.

Diagnosis. Large Rhynchoribates with attenuated rostrum without lateral teeth, slightly bent rostral setae; long and thin, setiform interlamellar setae and both lamellar and exobothridial setae short and very fine. Lamellar setae inserted on central part of prodorsum. Sensillus and most of notogastral setae spatulate distally. Prodorsum except interbothridial area without ridges and other significant sclerites. Prodorsum and lateral parts of pedotecta I and discidia covered by large, darker nodes. Pedotecta I and discidia very strongly developed. Some ventral setae distinctly different from other, setiform ones: epimeral setae 1b and 4c, aggenital setae and seta ad1 larger, flat and broadened, lanceate. Also some dorsal and lateral leg setae broadened distally, baculiform. Proral setae of leg IV short, thickened, thorn-like.

Description. Body length of holotype 911, ventral body length 835, maximum body width 532 (between tips of discidia). Prodorsum length 415, maximum prodorsum width 344. Body of paratype crushed, not allowing measurements, size similar to holotype.

Integument. Colour brown to red-brown, dark. Notogaster, anogenital area, legs except distal part of tarsi covered by amorphous and microgranular semi-transparent cerotegument, areas in vicinity of trochanters III–IV with filamentous and amorphous cerotegument. Parts of prodorsum covered by large cerotegument knobs appearing darker, with maximum diameter of tubercles 10–12. Large knobs cover large, H-shaped, area in central part of prodorsum anterior to lamellar setae, lateral walls of pedotecta I, surface of discidia, and partly trochanters IV dorsally. Bunch of transparent cylindrical „cells“ was observed on posterior part of notogaster between setae h2 ( Fig. 1 A), not closely attached to notogaster surface when seen in lateral view. It was difficult to judge, whether this structure belongs to the individual or not.

Prodorsum. ( Fig. 1 A). Rostrum conical, regularly attenuated, pointed. Edges of rostrum laterally without teeth. Longitudinal rostral furrow distinct, bifurcated from the area of ro insertions backwards. Most of prodorsum surface without particular cuticular structures, except of short interbothridial ridges running parallel from insertions of in anteriad. Anterior ends of ridges, where surface of prodorsum decline steeply, with short and irregular transversal cuticular thickenings. Parietal walls of acetabula I and opposing internal wall of pedotecta I thickened, appearing darker. Bothridia with quite strong walls, appearing dorsally almost quadrangular, positioned close to each other. Distance between axial margins of bothridial openings about 0,75 times distance between lateral edge of bothridium and tip of discidium. Discidium very strongly developed, large, projecting posteriad by beak-like tip above trochanter IV, similar but shorter projection situated under discidium ventrally. Rostral setae (ro) oriented anteriad, bent, slightly broadened and blunt at the tip, their length between 110–115. Setae in ( Fig. 2 C) long, narrow, setiform, pointed, longest of all prodorsal setae except sensillus, their length 145–152. Setae le, ex similarly shaped, very fine, setiform, short; length of le 60–62, ex 53–55. Sensillus very long (240–248), with long and only slightly bent stalk, with very slightly thickened head, covered by very fine granulation (cerotegument?).

Notogaster. Almost round in dorsal view, semiglobular ( Fig. 1 A). Anterior margin with rather distinct humeral tubercles and another pair of small, indistinct tubercles axially, behind bothridia. Without visible humeral carinae or cristae. 10 pairs of notogastral setae present, slightly differing in size and shape, all baculiform, with distal end blunt and covered by very fine granulation (similarly to sensillus). Setae c2 smoothest and without expansion distally, other setae distally expanded, expansion most developed on la, lp, h1, h2 and p1 ( Fig. 2 C). Setae p2 and p3 shortest (90–95), la–lp longest (130–150), length of seta c2 120–123. Notogastral lyrifissures difficult to observe, at usual places.

Gnathosoma. ( Fig. 1 B). Relatively short, with structure typical for genus. Infracapitulum relatively broad at base, setae h longer than m and a, curled. Setation of palp 2–1–3–8. Mentotectum broad, collar-like.

Epimeral region. ( Fig. 1 B). Surface of epimeral region without particular cuticular structures. Circumpedal ridges absent or indistinct, so discidial area not distinctly separated from epimere IV. Epimeral setal formula 3-1-3- 4; setae 1b and 4c ( Figs 1 B, 2D) bigger, flattened, with narrow marginal velum, longer than others (75–85). Other epimeral setae except 4a and 4b thin, setiform, 2a shortest (23–25). Seta 3a inserted on ventral side of pedotectum I, 4d on discidium. Only alveoli observed in positions of setae 4a (very close to aggenital seta) and 4b on both individuals, it was impossible to assess if the setae were broken or vestigial.

Anogenital area. ( Fig. 1 B). Genital opening distinctly smaller than anal opening, distance between them exceeding length of genital opening. Preanal sclerite rather narrow, inverted V-shaped. Genital plates pentagonal, anal plates almost semi-circular, with rugged anterior angles. 7 pairs of genital setae, all smooth, fine, setiform ( Fig. 2 D), about same length (around 50). Aggenital setae (ag, Fig. 2 D) similar to epimeral setae 1b and 4b, larger, elongated, flattened in the middle and pointed. 2 pairs of rather short (20–21), fine, setiform anal setae; an1 slightly posterior to midlength of anal plate, far from an2. Adanal setae unequally developed: ad2, ad3 fine, setiform and rather short (33–35), ad1 enlarged, similar to ag, but longer, less attenuated distally ( Fig. 2 D). Lyrifissures iad paraanal.

Legs. ( Fig. 2 A–B). Each leg with single strong claw. Setal formula (famulus included, solenidia in parentheses) as follows: leg I 1–5 –2(1) –4(2) –20(2), leg II 1–5 –1(1)–4(1) –17, leg III 2–3 –1(1)–3(1)–15, leg IV 1– 2 –2–3(1)–12. Homology of setae indicated in Table 1 . Solenidia φ1 and φ2 of tibia I setiform, pointed and bent distally, other solenidia fine, rather short, straight or slightly bent, attenuated (on genua) or blunt at the end. Leg setae differing in shape: dorsal setae of femora, antiaxial lateral setae of genua and tibiae similar to notogastral setae, more or less distinctly expanded distally (baculiform, Fig. 2 A–B). Other leg setae normal setiform or slightly longer and thicker, but always attenuated distally. Famulus short, simple, setiform. Proral setae of tarsus I simple, setiform, on leg IV modified, thickened at base, with short hyaline tip.

Roman letters refer to normal setae, Greek letters to solenidia (ε to famulus). Single prime (') marks setae on anterior and double prime (") setae on posterior side of the given leg segment. Parentheses refer to a pair of setae. Differences in Rhynchoribates (Rhynchoribatodes) dynastes n. sp. indicated by asterisks: *—whole pair of (l) present on genu II, **— pair (l) not observed in this species

Remarks. The new species belongs to the group of species from nominal subgenus, with rostrum without denticulation, prodorsum covered largely by tubercles of cerotegument, without complicated pattern of ridges, and with setae le distinctly shorter than in, inserted directly on the surface of prodorsum (with 3 known species: R. amazonicus Woas, 1986 ; R. spathulatus Balogh & Mahunka, 1969 ; R. spectabilis Balogh & Mahunka, 1969 ). R. danbartai n. sp. differs from all these species (and from all hitherto known species of the entire genus) by development of sensillus, which is dilated and obtuse at the end (spatulate), without long attenuated tip and much less bent than in most of other species. From R. amazonicus it differs in addition by long, setiform and distally attenuated setae in (in R. amazonicus thickened, with obtuse end), by setae le inserted on the surface of central part of prodorsum (in R. amazonicus on transversal sclerotised ridge), and by development of ventral setae: in the new species setae 1b, 4c, ag and ad1 are enlarged, while in R. amazonicus just setae ag and ad1 are similarly developed. R. spectabilis and R. spathulatus , in addition to sensillus, differ from the new species by differently developed rostral setae (thin, attenuated, bent laterad–reclinate), by notogastral setae, which are not smooth but have dentate or aciculate lateral margins, and by not enlarged epimeral setae.

Derivatio nominis. The species is dedicated to my friend, Odonata specialist and famous Czech musician, Dan Bárta, who co-participated at the expedition to French Guyana.

Figures

FIGURE 1. Rhynchoribates (s. str.) danbartai n. sp., holotype. A—dorsal view; B—ventral view. Scale bar: 200 µm.

FIGURE 2. Rhynchoribates (s. str.) danbartai n. sp. A—leg I; B—leg IV; C—notogastral setae, bothridium, sensillus and seta in; D—ventral setae. Scale bar: 50 µm.

Tables

TABLE 1. Leg setation and solenidia of adult Rhynchoribates danbartai n. sp., Rhynchoribates (Tectorhynchobates) jurobales n. sp., Rhynchoribates (Rhynchoribatodes) dynastes n. sp.

Leg Troch.	Femur	Genu	Tibia	Tarsus
I v'	d, (l), bv", v"	(l), σ	(l), (v), φ1, φ2	(ft), (tc), (it), (p), (u), (a), s, (pv), v', l", (pl), ε, ω1, ω2
II v'	d, (l), bv", v"	l'*, σ	(l), (v), φ	(ft), (tc), (it), (p), (u), (a), s,(pv), (l)**, ω1, ω2
III l', v'	d, l', ev'	l', σ	l', (v), φ	(ft), (tc), (it), (p), (u), (a), s, (pv)
IV v'	d, ev'	d, l'	l', (v), φ	ft", (tc), (p), (u), (a), s, (pv)