Lucasioides altaicus Gongalsky & Nefediev & Turbanov 2021, sp. nov.
Creators: name: Gongalsky, Konstantin B.
name: Nefediev, Pavel S.
name: Turbanov, Ilya S.
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Isopoda
Trachelipodidae
Lucasioides
Lucasioides altaicus

description: Lucasioides altaicus sp. nov.
Figs 1–7
Mongoloniscus sp. (pro parte)— Gongalsky et al. 2017: 26.
Material examined: Holotype, ³ (ZMMU, Mc-1420), Russia, southwestern Siberia, Altai Krai, Charyshskoye Dis-trict, near Komendantka, Altai State University (ASU) Field Station “Goluboi Utios”, 51°21ʹ38.0ʺN, 83°38ʹ02.7ʺE, 630 m a.s.l., N slope, plot 2, Betula pendula, Populus tremula, Pinus sylvestris, Spiraea chamaedrifolia, Bergenia crassifolia, hand sampling, 13 July 2016, leg. V.Yu. Slatina, Kh.Kh. Nedoev, S. T. Niyazov.
Paratypes: 1 ³ (ZMMU, Mc-1421); 1 ³, 1 ♀ (KG), Russia, southwestern Siberia, Altai Krai, Charyshskoye District, near Komendantka, ASU Field Station “Goluboi Utios”, 51°21ʹ44.3ʺN, 83°37ʹ42.6ʺE, 620 m a.s.l., N slope, plot 1, B. pendula, P. tremula, P. sylvestris, S. chamaedrifolia, B. crassifolia, soil sampling, sample 4 (0–10 cm), 12 July 2018, leg. V.Yu. Slatina, Kh.Kh. Nedoev; 3 ³³, 5 ♀♀ (ZMMU, Mc-1422); 1 ♀ (ZMMU, Mc-1424), 1 ³ (KG), 4 ³³ (ASU), location, date, and collectors same as holotype; 1 ³, 1 ♀ (ZMMU, Mc-1423), Russia, southwestern Siberia, Altai Krai, Charyshskoye District, near Komendantka, ASU Field Station “Goluboi Utios”, 51°21ʹ20.3ʺN, 83°37ʹ37.0ʺE, S. chamaedrifolia, Caragana arborescens, Lonicera tatarica on southern slope, 480 m a.s.l., soil sampling, sample 1 (0–10 cm), 6 September 2018, leg. Kh.Kh. Nedoev.
Diagnosis. Male exopod of pleopod 1 with concave tip and lower lobe is longer than the upper one; telson is elongated and shows sharp tip.
Description. Maximum body length: male 8.0 mm (holotype 7.2 mm), female 6.7 mm. Body dark grey-brown, with two rows of light grey-brown spots in medial part of coxal plates of pereonal segments 2–7 (Fig. 1A). Body relatively elongated, pleon forming no continuous margin with pereon (Fig. 1A). Dorsal surface of tergites smooth. Posterior edges of coxal plates of pereonites 1–3 straight, those of pereonites 4–7 curved (Fig. 2A). Head covered with scattered, sharp, triangular, dorsal setae (Fig. 1B). Noduli laterales on pereonites 1–4 located at approximately same distance to edge of coxal plates (Figs 2A, 3). Cephalic lobes poorly developed. Distal edge of median lobe rounded (Figs 1B, 2B). Telson with an elongated distal part, distal corner forming a triangle (Figs 2C, 3A).
Antennula with three articles (Fig. 2D); first article wide and long; second article 0.5 times as long as first; third article narrow as almost as long as first article, bearing tuft of setae at apex. Antenna of medium length, reaching pereonite 3; flagellum with two articles, proximal article slightly shorter than distal one (Figs 1C, 2E). Aesthetascs absent from apical articles of antenna.
Left mandible (Fig. 4A) with molar process carrying two teeth and lacinia mobilis with straight edge. Lobe covered by setae with three plumose penicils followed by row of 18–20 penicils located basal to lacinia. Right mandible smaller than left mandible, molar process with thee teeth and lacinia mobilis with two teeth and hairy bilobate lobe with row of 18–20 penicils (Fig. 4B). Maxillula (Fig. 4C) medial corner of inner endite with two strong hirsute setae.Apical edge of outer endite bearing nine spines divided into two groups; five medial spines slender and with split tips, and four lateral spines stouter and with simple tips. Tip of endite covered with brush of dense setae. Maxilla with bilobate edge, medial half of apical edge of inner lobe with brush of short dense setae (Fig. 4D). Inner margin with a subapical tubercle. Maxilliped with outer corner of endite with two acute tips and large spine near inner corner (Fig. 4E). Basal article of endopod with large spine.
Pereopods (Figs 2 F–H, 5). Ventral edge of male pereopod 7 carpus slightly curved.
Uropods (Fig. 1A, 2C) colored as dorsal surface of body. Exopods elongated, with widest part at 1/3 proximal distance (Figs 2C, 3A).
Male. Shape of genital papilla typical of the genus. All exopods at lateral margin with lungs. Exopod of pleopod 1 (Figs 6A, 7B) with long hind lobe bearing deep hollow and 9–10 setae at apex; inner margin slightly concave and devoid of setae. Endopod of pleopod 1 with a dorsal furrow and row of spines (Figs 6B, 7C, D). Pleopod 2 exopod triangular, with concave outer margin bearing 12 setae (Figs 6C, 7A); endopod much longer than exopod, narrow and parallel-sided (Figs 6D, 7A). Pleopods 3–4 exopods (Fig. 6 E–G) trapezoidal, slightly decreasing in size from 3 to 4. Pleopod 5 exopod triangular.
Etymology. The specific epithet refers to the locus typicus (the Altai Mountains).
Distribution and habitat. The species has been collected in the lowlands of Altai Mountains in the environs of Charyshskoye Village. The area supports a steppe habitat with S. chamaedrifolia, C. arborescens and L. tatarica bushes and scattered P. sylvestris, B. pendula and P. tremula stands with S. chamaedrifolia and B. crassifolia, growing on the southern and northern rocky slopes of a mountain, respectively. The above is the first record of the genus Lucasioides Kwon, 1993 from Russia, showing its presently northwestern range limit.
Remarks. The new species is assigned to Lucasioides since it has five pairs of pleopodal lungs; the flagellum of antenna consisting of two articles, and the position of the noduli laterales distinctive for the genus. This species seems to be particularly close to Desertoniscus mongolicus due to the similar shape of most body parts. Yet the taxonomic position of D. mongolicus within Desertoniscus needs to be revised. In the original description, Borutzky (1978) noted that D. mongolicus occupies a position intermediate between the genera Desertoniscus and Mongoloniscus, but in fact both D. mongolicus and L. altaicus sp. nov. also bear characteristics of both Protracheoniscus and Lucasioides (e.g., the position of the noduli laterales). However, these two species differ in the shape of the male exopod of pleopod 1: D. mongolicus has a longer upper lobe at the tip, while in L. altaicus sp. nov. the lower lobe is longer; D. mongolicus has antenna reaching only the posterior edge of tergite I, while they are longer in L. altaicus sp. nov. and reaching the posterior edge of tergite II. Within the genus Lucasioides, there are no species which could be mixed up with the new species. The morphologically closest species are L. isseli (Arcangeli, 1927) from China, L. sinuosus (Nunomura, 1987) from Korea and Japan, L. toyamaensis Nunomura 2008, L. sagarai Nunomura 2008, and L. yokahatai Nunomura 2010 from Japan (Nunomura 2008, 2010). The new species readily differs from all by the sharp and elongated telson, and in the shape of the exopod of pleopod 1. A molecular analysis is needed for the complex of those small species of Agnaridae, and a complete taxonomic revision of these sister genera is needed.
Phylogenetic analysis. A total of 11 nucleotide sequences were used to assess both species and intraspecific variation (Fig. 8): two of them were obtained from L. altaicus sp. nov., and further nine revealed earlier from Protracheoniscus politus (C. Koch, 1841) from Budapest, Hungary, P. pokarzhevskii Gongalsky et Turbanov, 2018, P. kryszanovskii Borutzky, 1957, P. nogaicus Demianowicz, 1932, P. major (Dollfus, 1903) and Desertoniscus zaitsevi Gongalsky, 2017 from the Republic of Kalmykia, Russia (Gongalsky et al. 2018). The loci of the COI mtDNA of Hemilepistus klugii (Brandt, 1833) and H. schirasi Lincoln, 1970 from Iran (Dimitriou et al. 2018) were used as outgroup taxa.
An analysis of the average values of pairwise sequence divergences (p -distances) of partial COI mtDNA (Table 2) shows that the intraspecific difference of two loci of L. altaicus sp. nov. is 0%, which indicates their complete identity. Within the considered species, p -distances range from 15.7% between L. altaicus sp. nov. and P. kryszanovskii up to 24.9% between P. politus and P. major. Similar genetic distances correspond to possible variations within the COI mtDNA gene for woodlice (Dimitriou et al. 2018).
It seems noteworthy that D. zaitsevi falls within the p -distances range for the genus Protracheoniscus, whose average values of pairwise sequence divergences reach 18.0% with P. major and 23.4% with P. nogaicus. Protracheoniscus appears to be paraphyletic (Fig. 8). However, this aspect and the question of the validity of the genera Desertoniscus Verhoeff, 1930 and Lucasioides Kwon, 1993 is to be left outside present paper, requiring a special study based on a more representative material.
description: Published as part of Gongalsky, Konstantin B., Nefediev, Pavel S. & Turbanov, Ilya S., 2021, A new species of the genus Lucasioides Kwon, 1993 (Isopoda, Oniscidea, Agnaridae) from Siberia, Russia, pp. 140-150 in Zootaxa 4903 (1) on pages 142-146, DOI: 10.11646/zootaxa.4903.1.9, http://zenodo.org/record/4422838