Ceratophysella anacopica, Babenko & Antipova, 2025

Ceratophysella anacopica sp. nov.

Figs 32–40 View FIGURES 32–35 View FIGURES 36–40

Type material. Holotype female, Georgia, Abkhazia, New Athos (Akhali Atoni), stony beach, close to water [ 43.0838°N 40.8135°E], 07.11.2015. M. Bizin leg. Deposited in MSPU. GoogleMaps

Paratypes 1 male & 3 females, same habitat as holotype.

Diagnosis. A middle-sized species of the denticulata - group, which differs from other members of the group by the following combination of characters: labium with only four papillae (papilla C absent), fine and uniform cuticular granulation, Ant. IV with four dorsal and two dorsolateral sensilla (sensilla S3? absent), moderate differentiation of dorsal setae with short straight macrosetae and curved fine microsetae, Th. II with only microsetae in a-row and usually three m-setae in dorsolateral group (m3, m4 & m5), axial setae on Abd. IV situated in almost parallel rows, and full sized furca with a typical set of seven setae.

Description. Body length without antennae 1.1–1.3 mm, holotype 1.3 mm. Habitus typical of the genus. General body colour in alcohol brownish, dark blue pigment diffusely distributed on dorsal side, ventral side paler. Integument granulation rather fine and uniform, although because of relatively small body size, Abd. V with only 8–10 granules between setae p1.

Antennae in length equal to head. Ant. IV with a simple or slightly divided apical bulb, six blunt sensilla (four dorsal, S0, S1, S2, and S4 and two dorsolateral (external), S7 and S8) cylindrical in shape, elongated and curved, well differentiated from common setae ( Fig. 35 View FIGURES 32–35 ); subapical organite (or) and microsensillum (ms) present as usual; ventral sensory file with few short blunt setae ( Fig. 36 View FIGURES 36–40 ). Eversible sac between Ant. III and Ant. IV prominent ( Fig. 35 View FIGURES 32–35 ). Ant. III with typical AO, the latter composed of two short inner club-shaped sensilla, two guard sensilla and ms on outer side ( Fig. 35 View FIGURES 32–35 ). Ant. I–II with 7 and 12(13) smooth common setae, respectively.

Head with 8+8 subequal eyes. PAO 2.6–3.1 times larger than adjacent ocellus, consisting of two long anterior and two rounded posterior lobes, an accessory boss invisible ( Fig. 37 View FIGURES 36–40 ). Labrum with usual set of 4/554 setae, its distal edge without distinct papillae. Labial palp as in C. succinea , with only four papillae (A, B, D, E; papilla C absent) and 14 guards, among them a1, b1, b2, d2, and e2 shorter and set on low papillae, a1 slightly thickened, lateral process (lp) rudimentary ( Fig. 38 View FIGURES 36–40 ). Number of proximal setae on labial palp in available material rather variable (5–7) and often asymmetrical. Basomedial field of labium (submentum) with four setae, basolateral field (mentum) with five setae, as usual. Head with 3+3 postlabial setae along ventral line. Maxillary head of the denticulata - type, with three teeth in main part and six usual lamellae, L.1 extending past tip of maxillary teeth and slightly expanded at apex. Outer maxillary lobe simple, with one sublobal hair as usual for the group.

Chaetotaxy complete and typical of the denticulata - group, dorsal setae poorly differentiated, especially so on head and thorax ( Fig. 32 View FIGURES 32–35 ), with macrosetae growing longer only on last abdominal segments ( Fig. 33 View FIGURES 32–35 ) and laterally on head. All setae fine and smooth, macrosetae usually straight, microsetae curved, sensorial setae longer than microsetae and clearly shorter than macrosetae on all segments except for Abd. V. Main peculiarities of tergal chaetotaxy: Th. II–III with all setae in a-row as microsetae of similar length; Th. II with three m-setae in dorsolateral group (m3–m5), whereas Th. III with two such setae (m4 and m5); macrosetae p2 and p3 subequal and about as long as 1.5 × p1 microsetae; a lateral ms present on Th. II as usual. Abdominal chaetotaxy: Abd. I–III with a2’ and m3–m4 present, macrosetae p4 on Abd. I only slightly longer than microsetae p3. Three pairs of axial setae (a1, m1 and p1) on Abd. IV situated in almost parallel rows. Abd. V without a2’, i.e. only 3 a-setae present between bases of macrosetae p1 and p5.

Chaetotaxy of legs 1–3 as follows: upper subcoxae—1, 3, 3 (among them, one macroseta on each subcoxa); lower subcoxae—0, (2)3, (2)3; coxae—3, 8, 8; trochanters—7, 7, 7; femora—14, 13, 12; tibiotarsi—19, 19, 18 setae, respectively. Tibiotarsal tenent setae (A1) acuminate, about as long as 1.2–1.3 × inner unguis edge ( Fig. 39 View FIGURES 36–40 ). Unguis with a small tooth in midsection of inner edge, lateral teeth invisible ( Fig. 39 View FIGURES 36–40 ). Unguiculus slightly exceeding the middle of unguis inner edge, with a clear basal lamella.

Ventral tube with 4+4 distal setae. Retinaculum with 4+4 teeth. Furca well-developed. Manubrium with 11–12 setae each side. Dens with seven dorsal setae; outer basal macroseta rather short, about as long as 0.5–0.6 × dens ( Fig. 40 View FIGURES 36–40 ), two distal inner setae thickened and slightly serrated in mid part. Mucro of usual shape with a high, triangular, outer lamella, 0.5 × as long as dens.

Anal spines light and relatively short, together with papillae about as long as inner unguis.

Etymology. Named after Anacopia, one of the ancient names of New Athos city where the new species was found.

Affinities. The most characteristic feature of the new species is undoubtedly the reduction of one of the labial papillae. This feature is not unique, but is known only for a limited number of species of the family Hypogastruridae . For the first time, such a structure of the labium was discovered by Fjellberg (1998) in C. succinea . The same author noted ( Fjellberg 1999) the absence of papilla C from further three species from two other genera of the family, namely, Schaefferia czernovi (Martynova, 1978) and two species of the genus Triacanthella ( T. perfecta Denis, 1926 and Triacanthella sp. from Australia). Up to now, a similar structure of the labial palp has been found in three additional species of the genus Ceratophysella : C. kapoviensis , C. michalinae and C lucifuga ( Packard, 1888) (see Skarżyński 2005, 2007), as well as in Hypogastrura hargrovei Skarżyński, 2007 . From three of the four abovementioned species of the genus Ceratophysella ( C. succinea , C. kapoviensis and C. michalinae ), the new species is easily distinguished by a complete set of dental setae (7 versus 6, 5–6 and 4–6 setae, respectively), whereas the American cave species C. lucifuga is characterised by the absence of an eversible sac from the antennae and the colouration (except for the eyespot), the trilobed apical papilla on the Ant. IV, and clearly differentiated long dorsal setae. However, the structure of the labium, by which one could easily distinguish the new species, is, unfortunately, unknown for most congeners. Even for species described since 1998, the absence or presence of labial papilla C is not always indicated. Thus, of 25 such species ( Bellinger et al. 1996 –2025), the structure of the labium has been described in 13, of which only one ( C. michalinae ) has a labial palp of the succinea - type.

Another characteristic feature of C. anacopica sp. nov. is a weak differentiation of dorsal setae, which is rather unusual for species of the denticulata- group. In the European fauna, the only species relatively similar in this character is C. caucasica Martynova, 1971 , in which, at least on the thorax, the setae are rather short and not very sharply differentiated. In addition, both species are characterised by the presence of three m-setae (m3, m4, m5) in the dorsolateral group on Th. II, which is more typical of the armata- group. Nevertheless, these two species are sharply different in a number of characters, in particular, C. caucasica is characterised by the presence of a large outgrowth of the integument with coarser granulation on Abd. V, antennae with 7(8) dorsal sensilla and a strongly developed ventral sensillar file. In addition, the labium of this species is of the usual denticulata- type with 5 papillae and 6 proximal setae (unpublished data).

Among the Asian species of the denticulata- group, a weak differentiation of dorsal setae and a relatively fine granulation of the integument are characteristic, for instance, of C. kutyrevae , described from Primorsky Krai. This species is characterised by the absence of colouration (except for the eyespot), a markedly reduced dorsal chaetotaxy, and the presence of only 6 dental setae. In addition, the labial palp in this species is of the denticulatatype, with five usual papillae and six proximal setae (unpublished data).

Based on the key to the Palearctic species of the genus ( Thibaud et al. 2004), the new species keys out either as C. annae ( Babenko, 1994; in Babenko et al. 1994), known from similar coastal communities from both coasts of the Pacific Ocean, or the widespread C. engadiensis ( Gisin, 1949) , or the boreal C. brevis ( Christiansen & Bellinger, 1980) . The former species is most similar to C. anacopica sp. nov. in the weakly differentiated dorsal setae and the relatively fine granulation of the integument, as well as in Ant. IV with only 6 dorsal sensilla, the weakly developed ventral file, the presence of three m-setae in the dorsolateral group on Th. II, and relatively short anal spines. Nevertheless, C. annae differs from the new species in the presence of only 2+2 setae on Th. I ( vs usual 3+3 setae in C. anacopica sp. nov.), clavate tibiotarsal setae ( vs acuminate in C. anacopica sp. nov.), 4 thickened dental setae ( vs only 2 such setae in C. anacopica sp. nov.), PAO with subequal anterior and posterior lobes, and the peculiar shape of the maxillary head ( vs the denticulata- type in C. anacopica sp. nov.). The other two species mentioned above, C. engadiensis and C. brevis , are in fact strongly different from C. anacopica sp. nov., even though they all share the absence of a2’ setae from Abd. V.

Distribution and ecology. The new species is known so far only from the type locality: the Black Sea coast of the Caucasus ( Fig. 1 View FIGURE 1 ), where it was discovered in conditions that are quite unusual for representatives of the genus (on a rocky beach in close proximity to water).