Pogonognathellus litoralis Kuprin et Potapov, 2019

Kuprin, A. V. & Potapov, M. B., 2019, Discovery of the first littoral species of the family Tomoceridae (Collembola), Far Eastern Entomologist 397, pp. 1-8 : 2-7

Pogonognathellus litoralis Kuprin et Potapov , sp. n.

http://zoobank.org/NomenclaturalActs/ D0309B84-9E7C-4771-BBC9-711C538455B6

Figs 1–12

TYPE MATERIAL. Holotype – female (on slide), Russia: Primorskii krai,

Vladivostok, Russkii Island, Vyatlina Bay, stony littoral, floatation, 26.VIII 2018,

coll. A. Kuprin & Yu. Shveenkova ( FCBV). Paratypes: Primorskii krai: same data as holotype, 1 female (on slide), 5 specimens (in alcohol) ( FCBV); Lazovsky

District, near Sokolovka, Sokolovskaya Bay, shingly beach, floatation, 20.IX 2011,

20 specimens (on slide), coll. M. Potapov, Y. Bu & Ch.-W. Huang (10 specimens in

MSPU, 10 specimens in SMNH).

OTHER MATERIAL. Russia: Primorskii krai, Vladivostok, Russkii Island,

Malyi Dzhigit Bay, stony littoral, floatation, 26.VIII 2018, 10 juv. (in alcohol), coll.

A. Kuprin & Yu. Shveenkova (FCBV); Vladivostok, De-Fries Peninsula, Uglovoy

Bay, stony littoral, floatation, 04.VI 2019, 2 specimens (in alcohol), coll. A. Kuprin

(FCBV); Fokino, Rudneva Bay, littoral (sand/algae), floatation, 07.VII 2018, 5

specimens (in alcohol), coll. A. Kuprin (FCBV).

DESCRIPTION. Female body size up to 3 mm. In alcohol body and head grey,

proximal part of legs paler, tibiotarsi, antennae and distal part of furca with bluish pigmentation ( Fig. 1 ). Eye spots black. In Hoera liquid on slides body greenish.

Head. Antennae as about 0.7–0.8 body length. Ratio Ant.I: Ant.II: Ant.III+IV as 1.0: 1.4-1.7: 9.0–10.0. Ant. I, II and basal part of Ant. III with scales. 6+6

ocelli. Labrum 4/554 and 4 back-curved spines, all setae smooth ( Fig. 3 ). Maxillary outer lobe with 4 sublobal hairs and trifurcate palp. Maxillary head with expanded ciliate lamellae and beard-like proximal projection as common for the genus ( Fig.

6). Lamella 1 rather broad, with field of numerous strong denticles and distal row of cilia, lamella 2 with distal row of cilia and many irregular rows in more proximal part, lamella 5 with long beard-like ciliate projection; lamella 6 reduced. Lamellae 2

and 3 close together and look fused to a single mass (as "2+3" in figure). Labial palp as common for the family: all papillae present, A, B, C, D, E with 0, 5, 0, 4, 7

guards, hypostomal setae H pointed, h1 as thick as H, h2 shorter and thinner.

Arrangement of guards associated with papilla B complex: guard a1 set on papilla

B, guards b1 and b4 set together on separate papilla, guards b2 and b3 also set on papilla detached from papilla B (as on Fig. 69 in Fjellberg, 1998). Basolateral,

proximal and basomedial fields of labial palp with numerous setae; as about in P.

flavescens (Fig: 93B in Fjellberg, 2007).

Dorsal chaetotaxy. Dorsal side of head with 2+4 anterior Mac (A2, A3, A5), 3+3

interocular Mac (S2, S5, S5i), 2+2 postocular Mac (Pa5, Pa6), and 2+2 posterior

Mac (Pa2, Pp3, Pe3) ( Fig. 9 ). Tergal macrosetae of body as in Figs 10–12 . Anterior

Mac on Abd.IV absent. Abd. III with 2+2 anterior and 4+4 posterior Mac.

legs; 3 – labrum; 4, 5 – hind claw, lateral (4) and outer (5) views; 6 – maxillary head,

maxillary claw shown separately. lat.tooth – lateral tooth, I, II, III – fore, mid and hind legs respectively.

Legs. Trochanteral organ reduced to 1+1 setae. Tibiotarsi of Leg III with 2 spiny inner setae, general formula for all legs 0-0-2 ( Fig. 2 ). Tenent hair apically spatulate, longer (1,05–1.20) than inner edge and shorter than outer edge of Claw

( Fig. 4 ). Claws with one distinct inner tooth, and often with indistinct second one on all legs. Pair of lateral teeth (pseudonychia) large, longer than half of outer side of enlarged, with big inner tooth, 0.8-0.9 as long as inner edge of Claw and almost as wide (ca. 0.9) as Claw width in its middle part.

mucro; 9 – macrosetae of head (A, S, Pa, Pp, Pe – macrosetae); 10–12 – macrosetae on dorsum (a – anterior chaeta, m – medial chaeta, p – posterior chaeta): 10 – Abd.III-V, 11 –

Th.II (the second bothriotricha not shown), 12 – Th. III-Abd.I.

5

Abdominal appendages. Ventral tube with numerous setae in anterior, posterior and latero-distal groups, covered by scales on anterior and posterior sides.

Retinaculum with 4+4 teeth and a seta, without scales. Manubrium with 8–11 large setae on each of lateral sides, with numerous scales on anterior sides and few ones along inner part of setaceous stripes on posterior side. Distal part of posterior side of manubrium with numerous setae of different size, among the largest ones 0-2+0-

2 straight. Manubrium: dens: mucro as 3.5–4.2: 4.7–4.8: 1. Basal part of dens with one large spine swollen in proximal part and often slightly curved, set on papilla, with numerous large setae, of which 1–2 straight. Medial part with 7–8

spines of which 2 distal distinctly larger ( Fig. 7 ). Dental spine formula I/ 5-6, II

(with 2–4 small spines in juvenile specimens of 1.5–2.0 mm). Spines simple. Basal spines much larger than two distal large spines. Mucro with 5–8 intermediate teeth

(3–4 in juvenile specimens of 1.5–2.0 mm) ( Fig. 8 ).

REMARKS. The new species sharply differs by several characters. Enlarged unguiculus is remarkable: it is as wide as claw and almost as long as its inner edge.

In all representatives of the family unguiculus distinctly thinner and at least 1.5

times shorter than inner edge. Lateral teeth are not detached from outer edge of claw that has been also unknown in the non-cave species of the family so far. For the genus, the presence of only one large basal spine on dens is shared only with P.

elongatus (Maynard, 1951), P. dubius (Christiansen, 1964) and P. magnibrunneus

Park, Bernard et Moulton, 2011, all are distributed in North America and differ from P. litoralis sp. n. by several significant features. Besides, the basal spine distinctly larger than distal spines in the new species (vs. subequal in other species of the genus). Presence of only one distinct inner tooth on claw is also unknown. In reference to the species groups, P. litoralis sp. n. is more close to “longicornis”

clade (Felderhoff et al., 2010) by 2+4 frontal macrosetae and presence of posterior macrosetae on head, absence of anterior macrosetae on Abd.IV, presence of seta on retinaculum and subequal short intermediate spines on dens. In these characters, P.

litoralis sp. n. resembles two species from NE China, namely P. mai Wang, Yu et

Zhang, 2013 and P. heterochrosatus Wang, Yu et Zhang, 2013 which also close to

“longicornis” clade while all three species differ from the clade by less number of spiny inner setae on tibiotarsi (0,0,2 instead 4+,4+,4+).

Lateral teeth integrated to outer edge of claw and enlarged unguiculus of the new species probably indicate close contact of legs to salt water on littoral where this species occurs. According to Christiansen (1965, 1988) foot complex of cave

Pseudosinella Schäffer, 1897 (Entomobryomorpha) undergoes complicated morphological changes if contacting water surface. Two tendencies, expansion of outer edge of claw and attenuation of unguiculus, concern the new species. The former tendency is well seen in Pogonognathellus litoralis sp. n. while its expanded unguiculus are hard to explain in terms of K. Christiansen. In Tomoceridae , Tritomurus veles Lukić ,

Houssin et Deharveng, 2010 ( Croatia, cave) and T. falcifer Cassagnau, 1958 ( France,

cave), contrary to P. litoralis sp. n., well agree with scheme of K. Christiansen by having very slender claw and unguiculus reflecting penetrating to thin film of water in hydropetric sites (Lukić et al., 2010). The elongated claw as a troglomorphic character in Collembola is well discussed by Vargovitsh (2019). Foot complex position “C” (in Fig. 4C in Christiansen, 1965) assumes contact of both claw and unguiculus along their longest region and can possibly elucidate morphology of unguiculus in the new species. In littoral forms, the expanded unguiculus often occurs (Strenzke, 1955) that call for comprehensive explanations as it was presen-

ted by K. Christiansen for cave species. Maxillary head of P. litoralis sp. n. does not undergo expected significant modifications which are widely known in other littoral Collembola (genera Archisotoma Linnaniemi, 1912 and Halisotoma Bagnall,

1949). Beard-like ciliate projection of lamella 5 looks longer ( Fig. 6 ) than in other species of the genus while other lamellae are like as common. Tomoceridae are hydrophylic group and are already armed with factually “littoral” fringed lamellae

(Fjellberg, 2007) and are possibly preadopted to liquid food of damp habitats.

DISTRIBUTION AND ECOLOGY. The new species is recorded along western coast of Japanese Sea in four distant localities of southern areas of Primorskii krai.

It was not found by us in appropriate sites of more northern areas (Terney and

Olga). P. litoralis sp. n. is a typical inhabitant of shingly organically enriched littoral of stony inlets, frequent in shingle mixtured with rotten wrack. The species was absent in litter of coastal forests nearby.

ETHYMOLOGY. New species is named after ecological preference.

Figures

Fig. 1. Appearance of Pogonognathellus litoralis Kuprin et Potapov, sp. n.

Figs. 2–6. Pogonognathellus litoralis Kuprin et Potapov, sp. n. 2 – spiny inner setae on

Figs. 7–12. Pogonognathellus litoralis Kuprin et Potapov, sp. n. 7 – spines on dens; 8 –