Protracheoniscus kryszanovskii Borutzky, 1957

Gongalsky, Konstantin B., Turbanov, Ilya S., Medvedev, Dmitry A. & Volkova, Julia S., 2018, Description of a new species of the genus Protracheoniscus Verhoeff, 1917 and redescription of Protracheoniscuskryszanovskii Borutzky, 1957 from the southeast of European Russia (Isopoda, Oniscidea, Agnaridae), ZooKeys 801, pp. 189-205 : 189

Protracheoniscus kryszanovskii Borutzky, 1957

Material examined.

1 ♂, 1 ♀, 6 juveniles (ZMMU Mc-627); [USSR, Stavropol Region, bank of lake] Manych, 4 km NE of Divnoe, 20.05.1950. O. Kryzhanovsky leg. 2 ♂♂, 5 ♀♀ (ZMMU); Russia, Republic of Kalmykia, 1 km W of Tsagan Nur, bank of lake Sarpa. 27.04.2017 (47.362, 45.201), K. Gongalsky leg. 4 ♂♂, 8 ♀♀ (private collection of K. Gongalsky), same date and location.

Diagnosis.

Protracheoniscus kryszanovskii is characterized by the shape of cephalic lobes; exopod of male pleopod 1; and dactylus of male pereopods 6 and 7 widened in the middle ( Borutzky 1957).

Re-description.

Somatic characters. Maximum body length: male 21 mm; female 14 mm ( Borutzky 1957). Body color dark grey-brown white or yellow spots at base of coxal plates of pereonites 2-7(Figure 1B). Dorsal surface of tergites smooth. Posterior edges of coxal plates of pereonites straight (Figure 6B). Distal part of head covered with scattered sharp triangular dorsal scale-setae (Figure 6A). Noduli laterales on pereonites 3-4 located distinctly more distant from coxal plates lateral edges (Figure 6B). Body relatively elongated; pleon outline not continuous with pereon (Figure 1B). Cephalic lobes well developed; median lobe rounded (Figure 6C). Telson with distal part elongated and distal corner forming sharp triangle (Figure 6D).

Appendages. Uropods (Figure 6D) colored as dorsal surface of body; exopods elongated, widened in the middle. Telson not reaching endopods of uropods. Antennula with three articles (Figure 6E); first article wide and relatively long; second article 1.5-2 times shorter than first; third article almost as long as second and narrow, bearing a tuft of setae at apex. Antenna long, reaching pereonite 3 (Figure 1B); flagellum with proximal article 1.5 times longer than distal one (Figure 6F). Left mandible (Figure 7A) with pars incisiva with two teeth and lacinia mobilis with straight edge; molar penicil with ca. 12-15 setae. Right mandible smaller than left with pars incisiva with three teeth and lacinia mobilis with two teeth bearing five penicil setae; molar penicil with 15-18 setae (Figure 7B). Maxillula (Figure 7C): medial corner of inner endite with two strong penicils and sharp tip; apical edge of outer endite with 4 + 4 teeth, four of which apically cleft. Maxilla with bilobate edge, medial half of apical edge of inner lobe with a dense brush of short setae (Figure 7D); inner margin with subapical tubercle. Maxilliped with outer corner of endite with two acute tips and large spine near the inner corner (Figure 7E). All exopods of pleopods with monospiracular covered lungs.

Male: Pereopods (Figure 8 A–C): Pereopod 1 (Figure 8A) with a brush of setae with split tips on merus and carpus; dactylus of pereopods 6 and 7 widened in the middle (Figure 8C). Genital papilla slightly inflated at tip (Figure 8H). Exopod of pleopod 1 (Figure 9A) with almost rounded tip and numerous small setae at apex, outer margin slightly concave with minute setae; endopod of pleopod 1 with triangular apical part with tuft of long setae on inner margin (Figure 9B). Pleopod 2: exopod triangular with straight outer margin bearing more than 15 setae (Figure 9C); endopod much longer than exopod, narrow, with parallel sides (Figure 9D). Pleopod 3-4 exopods (Figure 9 E–F) trapezoidal, slightly decreasing in size. Pleopod 5 exopod triangular, with sharply rounded corners (Figure 9G).

Remarks.

This species belongs to the central Asian group of Protracheoniscus characterized by the position of noduli laterales on pereonites 3 and 4 at a distance from the lateral edge (Borutzky, 1957). The distinctive feature of the genus is the male dactylus of pereopod 6 and 7 widened in the middle. This species is the morphologically closest to P. major (Dollfus, 1903), from which it differs in lacking the enlargement of dactyli of male pereopods 6 and 7 (see Gruner 1966; Tomescu et al. 2016). Protracheoniscus major is one of the dominant woodlice species in Kalmykia and broadly distributed around the Caspian Sea ( Kashani and Hamidnia 2016). The study of several specimens from the type locality confirmed the identity of our specimens with the type series designated by Borutzky (1957). Both the old collection and recent one of P. kryszanovskii showed substantial variability in the endopodite of the male pleopod 1.

Distribution.

The species has been found between the Volga and Vostochnyi Manych Rivers so far (Figure 10). It occupies steppes of Kalmykia ( Artemisia austriaca , Festuca valesiaca , Tanacetum achilleifolium ) and is common in various biotopes being one of the dominant species in the region. The species prefers salted soils, namely the banks of lakes with salted water. In the surroundings of Kamyshin (Volgograd Region) it was found in the burrows of Spermophilus sp. and in leaf litter ( Borutzky 1957).

Phylogenetic analysis.

The results of the pairwise distance analysis based on the analysis of the mtDNA COI gene (Table 2) show that the difference between P. politus and P. pokarzhevskii sp. n. by mtDNA COI is 23.0%. The differences between P. pokarzhevskii sp. n. from the types of outgroup taxa by mtDNA COI range from 24.0% to 30.0%. The results obtained indicate the species’ independence of P. pokarzhevskii sp. n. and a considerable divergence from the morphologically close P. politus .