Ceratophysella skarzynskii Weiner & Sun

Weiner, Wanda Maria, Xie, Zhijing, Li, Yu & Sun, Xin, 2019, Ceratophysella species from mushrooms in China (Collembola, Hypogastruridae), ZooKeys 822, pp. 67-77 : 68-70

Ceratophysella skarzynskii Weiner & Sun sp. n. Figs 1, 2, 3, Table 1

Type material.

Holotype: preadult male, China: Jilin: Changbai Mountains, alt. 2000 m, on Russula sp., leg. Xin Sun, 29 July 2015. Paratypes: 10 females and one juvenile, the same data as holotype. Type material: the holotype and 8 paratypes are housed in IGA-CAS, China, two paratypes in ISEA-PAS, Poland.

Diagnosis.

Dorsal chaetotaxy of type B with serrated chaetae. Maximal length 1.09 mm. Antennal segment IV with bi- or trilobed apical vesicle and ventral sensory file with 30-32 peg-like s-chaetae. Dens with seven chaetae, five of them modified.

Description.

Body length 0.9-1.09 mm (holotype: 1.07 mm). Body colour violet or blue in alive specimens, grey or grey-black in alcohol, ventrally pale. Granulation rather coarse, 10-14 granules between chaetae p1 on Abd. V ( Yosii’s parameter).

Antennae. Ant. IV with bilobed or trilobed apical vesicle (av), subapical organite (or), dorso-lateral microsensillum (ms), seven cylindrical, subequal sensilla (dorsal S0, S1-4, dorsolateral S7-8), ca. 30 small, peg-like sensilla and one subcylindrical sensillum in ventral sensory file (sensory rasp) (Fig. 2A, B). Ant. III-organ with two long (external) and two short (internal) curved sensilla (Fig. 2A). Microsensillum on ant. III present. Eversible sac between Ant. III–IV present (Fig. 2B). Ant. I with seven chaetae, Ant. II with 13 chaetae.

Head. Ocelli 8 + 8. Postantennal organ 1.5 times as large as single ocellus with four lobes of which the anterior pair is larger than the posterior pair (Fig. 2C). Accessory boss present (Fig. 2C).

Labrum with 5, 5, 4 chaetae, four prelabrals present. Head of maxilla of the C. armata type. Maxillary outer lobe with two sublobal hairs. Labium of the C. armata type, with five papillae ( A–E) and six proximal chaetae. Guard chaetae a1, b1-2, d2, e2 and lateral processus (l.p.) as accessory papillae with short terminal sensillum. Guards b3-4, d3-4, and e1-6 with long sensilla. Dorsal guards b3-4, d3-4, and e3 distally expanded and flattened.

Chaetotaxy. Differentiation of dorsal chaetae into micro-/meso- and macrochaetae quite distinct (Figs 1A, 1B, 2D, 3C). Arrangement of chaetae on head typical for the genus, spine-like chaetae absent. Cephalic chaetae d2, 4, v2, p3,4, g1, 5, l01, l11 as macrochaetae. Dorsal chaetotaxy of B type (sensu Gisin 1947, Bourgeois and Cassagnau 1972, and Babenko et al. 1994) (Fig. 1B). Chaetae of medium length, pointed and serrated. Th. I with macrochaetae p4, without p2. Th. II–III with macrochaetae p2 (shifted forward), p5, 6, m5, chaetae m4 and m5 (Th. II with m4'and microsensillum ms), chaetae p4 m6 as sensorial chaetae s, chaetae a2 as long as a3. Abd. I–III with macrochaetae p2,6, sensorial chaetae s = p5. Abd. IV with macrochaetae p1, 3, 6, s-chaetae as p4. Abd. V with macrochaetae p1, 5, 4 + 4 a-chaetae inside two macrochaetae p5 (a2, 2' absent, chaeta a5 straight above p5) (Figs 1B, 3C). Body s-chaetae relatively long, but shorter than macrochaetae, only on Abd. V as long as macrochaetae p1, 5 (Figs 1A, B, 3C).

Tibiotarsi I, II, III with 19, 19, 18 chaetae respectively, including one acuminate tenent hair A1 each, femora with 13, 13, 12 chaetae, trochanters with 7, 7, 7 chaetae, coxae with 3, 7, 8 chaetae, subcoxae II with 0, 3, 3 chaetae, subcoxaeI with 1, 2, 3 chaetae. Claws with inner tooth and two pairs of lateral teeth. Empodial appendage with broad basal lamella and apical filament reaching slightly below inner tooth (ratio empodial filament: inner edge of claw = 0.47) (Fig. 3A). Ventral tube with 4 + 4 chaetae.

Retinaculum with 4 + 4 teeth. Furca well developed. Ratio dens + mucro: inner edge of claw III = 2.11: 1, ratio dens: mucro = 1.79: 1. Cuticular skeleton of furca well visible. Dens with uniform granulation and seven dorsal chaetae of which five are modified, two strongly thickened and three moderately so; basal macrochaeta longer than others chaetae, shorter than dens (3/5 of its length). Mucro boat-like with clear outer lamella (Fig. 3B, D).

Anal spines as long as inner edge of claw III slightly curved, situated on basal papillae, colourless (Figs 1B, 3C).

Etymology.

The species is cordially dedicated to our colleague and friend Dr Dariusz Skarżyński, a prominent Polish specialist in Hypogastruridae , Collembola .

Remarks.

The new species belongs to the armata -group of species, group B (Abd. tergum IV with p1 as macrochaeta) and subgroup B2 (Abd. tergum IV without chaeta p3) ( Bourgeois and Cassagnau 1972). Among the species which could belong to this subgroup, C. skarzynskii is most similar to four species: C. denisana (Yosii, 1956), C. empodialis Babenko, 1994 (in Babenko et al. 1994), C. longispina (Tullberg, 1876), and C. scotica (Carpenter & Evans, 1899), due to the absence of transformed into spines, spine-like chaetae or spine-like integumentary protuberance on the head orAbd. V. They differ in the shape of the apical vesicle, the number of modified chaetae on the dens, the number of peg-like chaetae in the ventral sensory file on Ant. IV, length of empodial appendage,in the type of dorsal chaetae (serrated or smooth), and in the number of sublobal hairs on maxillary palp (one or two). A comparison of these species is presented in Table 1.