Coronabelba unicornis, Kolesnikov & Miko, 2022

Kolesnikov, Vasiliy B. & Miko, Ladislav, 2022, Taxonomy of European Damaeidae X. Description of Coronabelba unicornis n. gen., n. sp. (Acari, Oribatida, Damaeidae) from Abkhazia, with comments on genusMetabelba Grandjean, 1936, Acarologia 62 (2), pp. 340-351 : 343-350

publication ID	https://doi.org/ 10.24349/1khj-v25f
publication LSID	lsid:zoobank.org:pub:2717199D-C77A-4A5A-AA88-723C8F553488
persistent identifier	https://treatment.plazi.org/id/2B812841-973F-46E2-B815-6E682224E61D
taxon LSID	lsid:zoobank.org:act:2B812841-973F-46E2-B815-6E682224E61D
treatment provided by	Felipe
scientific name	Coronabelba unicornis
status	sp. nov.

Treatment

Coronabelba unicornis n. sp.

Zoobank: 2B812841-973F-46E2-B815-6E682224E61D

( Figures 1–5 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 )

Diagnosis — Body size: 470 × 260. Body surface and legs covered by columnar cerotegument ( Figures 1A View Figure 1 , 5 View Figure 5 ). Prodorsum without tubercles Da (, Dp, Ba, Bp and La absent), apophysis P absent. With medial peaked prodorsal protuberance in the interbothridial region appearing as flat horn oriented anteriad. Between bases of lamellar setae there is a small sclerotized ridge (anteroprodorsal tectum). Bothridial seta short, smooth, with flagellate tip, covered distally by dense cerotegument creating “head”. Seta ex particularly strong, curved, claw-like. Notogastral setae spiniform, inserted on distinct apophyses, particularly posterior apophyses (row h) may be as long as the seta or even longer. Ventral tubercles Va absent, Vp faintly distinguishable as indistinct thickening; E2 absent. Parastigmatic tubercle Sa subtle,

quite long, straight spiniform and narrow, Sp faintly distinguishable, flat. Discidium quite long, spiniform, slightly curved, pointed, directed laterad. Epimeral setal formula: 3-1-3-4, setae situated on microtubercles. Legs moniliform, short, formulas of leg setation and solenidia: I (1–9–4–4–20) [1–2–2], II (1–9–4–5–17) [1–1–2], III (4–9–4–5–17) [1–1–0], IV (3–9–4–5–14)

[0–1–0]. Length of solenidia on genua and tibia II–III slightly longer than respective companion setae; solenidia φ 1 three times as long than 2 φ, φ 2 and ω 1 on tarsus I curved.

Description of adult — Measurements. Body length: 470, maximum notogastral width 260.

Integument. Body color yellowish brown to medium brown. Cerotegument ( Figures 1A View Figure 1 , 5 View Figure 5 ) with short, columnar excrescences. All leg femora with uneven mesh cerotegument under the columnar. Underlying cuticle mostly smooth, but faintly granular on lateral part of prodorsum and on tubercles. Genital plate with bumpy cuticle ( Figure 1B, C View Figure 1 ). Gastronotic exuviae (scalps) carried on notogaster ( Figures 4 View Figure 4 A-D, 5E, F), but without significant amounts of organic debris or soil particles.

Prodorsum ( Figure 1A, C View Figure 1 ). Rostrum blunt with weakly defined nose-like protuberance on dorsal side. Propodolateral apophysis absent. Tubercles Da, Dp absent; in Da place there are underdeveloped cuticle eminences; dorsosejugal Ba (, Bp) and lateral (La) tubercles absent. With medial peaked prodorsal protuberance in the interbothridial region. Parastigmatic apophyses Sa, subtle, straight spiniform and narrow, Sp faintly distinguishable, flat. Rostral and lamellar setae similar in length (42–43), smooth, setiform; ro slightly thinner than le. Between the bases le there is a small sclerotized ridge apt (, Figure 1A View Figure 1 ). Interlamellar seta (41) two times shorter than bothridial setae, setiform, smooth, inserted on tubercular apophysis. Exobothridial seta (20), setiform, curved anteromediad, smooth. Bothridial seta (70–90) smooth, setiform, with flagellate tip. Small, pore-like opening present behind insertion ex of, distinct pore visible also in lateral view behind acetabulum II in sejugal area. Distinct fields of sigillae (muscle insertions) present on prodorsum, two anteriad – anteromediad to bothridium and in, one in interbothridial area ( Figure 1A View Figure 1 ). Posterior edge of two posterior fields strengthened and more sclerotised.

Notogaster ( Figures 1A, C View Figure 1 , 4D, E View Figure 4 ). Notogaster conical in lateral view, with highest point shifted posteriad; anterior part of notogaster distinctly flattened. Notogastral setae c 1 –(h 1:

30–35, ps 1 – ps 3: 20–25) shorter than the distance to next more posterior seta, strong, smooth erect spines. Notogastral setae inserted on large protuberances ( Figure 4E View Figure 4 ). Distance c 1 – c 1 shorter than c 2 – c 2. Seta c 1 directed forward. Posterior notogastral setae p 1 (– p 3) setiform, with a sharp tip, without large protuberances. Circumgastric row of muscle sigillae distinct, well visible. One pair of minute light spots present on notogaster between to insertions of setae la and lm.

Gnathosoma ( Figure 3 View Figure 3 ). Subcapitulum longer than wide (110 × 70–76). Subcapitular setae

(a, m, h) similar in length (25–27), setiform, slightly barbed. Adoral seta (8) setiform, thin, smooth. Palp (88–95) with setation 0–2–1–3–9(+ω). Solenidion bacilliform, pressed to surface of palptarsus mediobasally. Postpalpal seta (7) spiniform. Chelicera (110) slightly narrowed, view.

position of teeth is shown in Figure 3C View Figure 3 ; seta cha (30) curved in the central part, with short barbs on external curvature and attenuated tip, seta chb (23) straight, distally bent and with fringe of diminishing barbs. Trägårdh’s organ (36) elongate triangular. Chelicera with three minute teeth on dorsal part.

Epimeral and lateral podosomal regions ( Figure 1B, C View Figure 1 ). Epimeral tubercles (E2) absent.

Ventral tubercles Va absent, Vp very weakly expressed, in the form of a slight rounding.

Ventrosejugal furrow deep, body distinctly narrowed between acetabula II and III. Epimeral setal formula: 3–1–3–4. Setae 1a, 1b, 1c, 2a, 3a, 3b, 3c, 4a, 4b, 4c and 4d situated on microtubercles. Epimeral setae comparatively long, smooth, thin, with attenuate tips. Epimeres with well visible muscular sigillae, particularly closer to axial part. Discidium well developed,

spiniform, pointed, directed laterad.

Anogenital region ( Figure 1B, C View Figure 1 ). Six pairs of genital (20–29), one pair of aggenital (32),

two pairs of anal (25) and three pairs of adanal (20–24) setae, all smooth, setiform, subequal in length, similar to epimeral setae. Distance ad 3 – ad 3 more than ad 2 – ad 2. Lyrifissure iad apoanal, oblique and divergent from body axis posteriad. Anal lyrifissure present.

Legs ( Figures 2 View Figure 2 , 5A–D View Figure 5 ). Legs segments with distinctly swollen distal parts (moniliform),

except tarsi, where swollen part is proximal. All legs distinctly shorter than body, leg IV longer than rest of legs ( Table 1). Leg setae comparatively long and strong, pointed; smooth or slightly barbed. Formulas of leg setation and solenidia: I (1–9–4–4–20) [1–2–2], II (1–9–4–5–17) [1–

1–2], III (4–9–4–5–17) [1–1–0], IV (3–9–4–5–14) [0–1–0]; homologies of setae and solenidia indicated in Table 2. Famulus setiform, emergent, relatively long. Solenidion of genua I, II and III each coupled with companion seta d, as well as solenidion of tibiae II and III. Length of solenidia on genua and tibiae II–III slightly longer than respective companion setae; solenidion φ 1 three times as long than 2 φ, φ 2 and ω 1 on tarsus I curved; solenidion on tibia IV not longer than tibia itself.

Ontogeny — Unknown. However, larval and nymphal exuvia ( Figures 4 View Figure 4 A-D, 5E, F) carried on the notogaster by adults. Larval notogastral setae strong, moderately long, darkly pigmented, and mostly with short barbs. Larval setae c 1 are directed towards each other, h 1

long (length as l). Nymphal notogastral setae strong, moderately long, darkly pigmented, and mostly with very short barbs; setae h 1 and ps 1 short, thin. Cornicle very short, thickened, conical; it uniformly narrowing toward apices, blunt, with the non-split distal part, situated at the level of setae h 2 – h 3 insertions of the adult.

Type material — Holotype (female) and paratype (females) Abkhazia ( Georgia), East Abkhazian region , Tkvarcheli District, surroundings of the village of Akarmara, beechlaurelcherry forest, 42°51′46″N, 41°46′15″E, 550 m a.s.l, soil, 20.III.2021 (coll. I. Turbanov). GoogleMaps

Type deposition — Holotype (female) and paratype (females) are stored in ZISP. All specimens are preserved in a 70% solution of ethanol with a drop of glycerol.

Etymology — The specific name “ unicornis ” refers to the medial peaked prodorsal protuberance in the interbothridial region.

Remarks — The new species is morphologically similar to Coronabelba platynotus Grandjean, 1954 n. comb. in form of notogaster and notogastral setae, Sa and dis. However,

the new species differs from the latter by the absence Da and Dp (versus enantiophysis D present), the presence of median, peaked prodorsal protuberance in the interbothridial region (versus slight gentle elevation only), poorly developed Sp (versus small, but distinct Sp present), long and curved solenidion 2 φon tibia I, three times longer than 2 φ(versus φ 1 more than 5

times longer than φ 2), solenidion ω 1 on tarsus I curved (versus straight), dorsal notogastral setae inserted on large apophyses, claw on leg I particularly long, about one third of tarsus I length (versus shorter claw, roughly one fifth of tarsus I length C in. platynotus ).

Discussion — Generic concepts of Metabelba highlight usually increased number of setae on moniliform legs, particularly on trochanters III-IV and on femora, and presence of companion seta d on tibia II and III, while on tibia IV the solenidion is usually long, tactile and without companion seta. Together with quite similar body shape and abundant cerotegument in thick layers it puts together quite numerous species, many of them insufficiently known or poorly described. Subias (2004, online amendment 2021) lists 30 species of the genus, equally divided in 2 subgenera. Yet, morphological differences between the species include differences in characters, which were regarded as generic in other damaeid oribatids, for example presence/absence of apophysis P, development of tubercle L, or differences in presence of companion setae d on tibia. As most of the characters seem to be very stable within the group, we argue that observed differences need to be considered at generic level. In Metabelba , as defined by Miko (2006) and Mourek et al. (2011), presence of 10 setae on femora I and II is a typical character, and exemption mentioned in diagnosis (presence of nine setae) was related to Grandjean’s M. platynotus only. Already Grandjean (1954) noted different femoral setation of M. platynous , and highlighted also the uniqueness of the general structure of body and cerotegument of his species, indicating that it may belong to different taxon at generic level, as already mentioned. C. unicornis n. sp. is very similar to Grandjean’s species and shares all the important characters which differentiate both species from Metabelba all species. They have similar form of notogaster (elongated ovoid, conical in lateral view), spiniform notogastral setae inserted on distinct tubercles or apophyses, same number (9) of setae on femur

I and II, and columnar cerotegument, present in sejugal and interbothridial region. There is therefore no doubt about the relationship between the two species, and about clear difference to other Metabelba species. This led us to follow the view of Grandjean (1954) and propose new genus as defined here and discussed further.

From all Metabelba species, only M. (Pateribelba) denscanis Mourek, Miko et Bernini,

2011 is exceptional in having conical notogaster, but clearly different from Coronabelba n. gen., with generally circular shape in dorsal view, without flattening in anterodorsal side and without specific shape and insertions of notogastral setae on apophyses or distinct tubercles.

It resembles rather notogaster of Belba species as discussed recently by Miko (2021) In both Coronabelba n. gen. species, notogaster is differently shaped, noticeably more elongated and oval/ovoid in dorsal view, maximum notogastral height is at level setae lp -h 3 (in M. (P.) denscanis with maximum notogastral height at level setae lm -lp), and clearly overhangs in posterior part. The form of notogastral setae of C. platynotus n. comb. and C. unicornis

n. sp. and their insertions was not observed in all other species of Metabelba . There are also differences in the shape of cerotegument excrescences mentioned by Grandjean (1954), but they are not universal: most species of Metabelba have filamentous (“cottony”) cerotegument, but some have it shaped differently (e.g. M. (P.) denscanis with irregular excrescences, M.

(P.) centurion Miko, Mourek et Ermilov, 2014 with granular/tubercular cerotegument or

M. (M.) propexa ( Kulczynski, 1902) with granular /columnar cerotegument), however still different from columnar form in Coronabelba n. gen., Coronabelba platynotus n. comb. and C. unicornis n. sp. have a well developed and quite deep prodorsal furrow, well visible in lateral view. The prodorsal protuberance, which is absent or only slightly indicated Metabelba in species, is elevated in Coronabelba n. gen., and transformed into a pointed protrusion at C. unicornis n. sp.

Another character supporting the separation of the new genus is the development of cornicle k on nymphal exuvia, which could be observed on our material. According to Ermilov (2012), Metabelba is characterized by long cornicles, with weakly dilated proximal part and split distal part. In C. unicornis n. sp., we observed short cornicles, without split distal part, reminding cornicles of Damaeus Koch, 1835 .

Following separation of Coronabelba n. gen., definition of Metabelba as presented in Miko (2006) and Mourek et al. (2011) can be narrowed, with no exceptions from the rule of 10 setae present on femur I and II. At the same time, we believe that presence of well developed seta d on tibia IV on M. (Neobelba) pseudopapillipes ( Bulanova-Zachvatkina, 1967) and its absence on all other species placed into subgenus Pateribelba does not allow to consider Neobelba and Pateribelba to be the same taxon, despite of their rather high similarity otherwise. Therefore, we support the concept of Metabelba with nominal subgenus and two other separated subgenera mentioned. Specific differences observed on some Metabelba species (e. g. M. (P.) denscanis and M. (P.) centurion ) require further assessment, as regards their subgeneric placement.