Two new species of the genus Leenurina Najt & Weiner, 1992 (Collembola, Neanuridae, Caputanurininae) from Primorskij Kraj (Russia)

Abstract Leenurina khualaza sp. n. and Leenurina pomorskii sp. n., two new species from East Russia (Primorskij Kraj) are described. They are closely related to Leenurina jasii Najt & Weiner, 1992 from North Korea, from which they differ mainly in the number of tibiotarsal chaetae (19, 19, 18 in the new species versus 18, 18, 17 in Leenurina jasii), several chaetotaxic features and organization of dorsal granulation. The two new species may be separated by tertiary granulation (large areas fringed with large secondary granules in Leenurina pomorskii, small rounded or hexagonal areas with smaller secondary granules in Leenurina khualaza), coloration (light blue in Leenurina khualaza versus white in Leenurina pomorskii) and number of eyes (2+2 eyes in Leenurina khualaza versus 3+3 eyes in Leenurina pomorskii). An updated diagnosis of the genus Leenurina Najt & Weiner, 1992 and a key to species of Caputanurininae are given.


introduction
Caputanurininae is a small subfamily of Neanuridae defined by a remarkable synapomorphy, unique among Collembola: the fusion of prothoracic tergite to head. It includes two genera: Caputanurina Lee, 1983and Leenurina Najt & Weiner, 1992. Koreanurina Najt & Weiner, 1992, assigned to Pseudachorutinae, is very similar to these genera, but its prothorax is separated from head (Najt and Weiner 1992). These three genera represent different degrees in head-prothorax fusion, from separate to completely fused, challenging the validity of the subfamily Caputanurininae as currently defined. Najt and Weiner (1992) established the genus Leenurina for two species: L. jasii Najt & Weiner, 1992 from North Korea as type species, and Caputanurina nana Lee, 1983 from South Korea. This genus is closely related to Caputanurina Lee, 1983, the nominal genus of the Far Eastern subfamily Caputanurininae. Differences between these two genera are summarized in the Table 2 of Najt and Weiner (1992: 204) and in Table 1 of the present paper.
Caputanurininae and the related genus Koreanurina are only known for temperate regions of Far-East Asia, i.e. South Korea (Lee 1983), North Korea (Najt and Weiner 1992), and northeastern China (Wu and Yin 2007).
Among a large material of Collembola collected in Primorskij Kraj, two new representatives of the genus Leenurina were found. They are described in this paper, and led us to correct and complete the diagnosis of this genus. They are the first Caputanurininae described from Russia, though an unidentified species of Caputanurina was already mentioned from Far East Russia -South Primorie (Kuznetsova 1988

Material and methods
The specimens were extracted from forest litter samples using Berlese funnels, and stored in 90% ethanol. They were cleared in lactic acid, mounted on slide in Marc-André II and examined using a microscope Leica DMLB. Photographs were taken with a ProgRes C3 camera mounted on the microscope, using either phase contrast (Fig. 6) or DIC interferential contrast (Figs 2A,4,5). Chaeta numbering in the text and figures follows Yosii (1960) and Cassagnau (1974).

Neanuridae Caputanurininae
Leenurina Najt & Weiner, 1992 http://species-id.net/wiki/Leenurina Type species: Leenurina jasii Najt & Weiner, 1992 Diagnosis. Body wide, flattened dorso-ventrally. Thoracic tergum I fused to head. Suture between abdominal tergum IV and V normal or as a shallow inverted V. Integument strongly granulated dorsally, with tertiary granulations variously arranged and underlying of hexagonal regular reticulations on head, thorax II and III, and abdomen I to V. Eyes and postantennal organ located dorsally. Postantennal organ made of 9-14 entire vesicles in one row. Mandibles with five teeth, maxillae thin. Labial organite x present. Papillated chaeta L absent on labium. Antenna with distinct apical vesicle. Antenna IV with 6 thickened sensilla and one microsensillum dorsally. Dorsal chaetotaxy of short and pointed ordinary chaetae and thin s-chaetae. Chaetal arrangement strongly disrupted on head, with a large central area devoid of chaetae. Dorsal chaetotaxy reduced. Claw toothless. Furca reduced to two small swellings, each with one chaeta.
Discussion. On thoracic terga, p1 correspond to chaeta m1 of Najt and Weiner 1992, and p2 to p1. As a result, the s-chaeta is assumed to be in p4 (p5 as in Najt and Weiner 1992). Leenurina differs from Caputanurina, the other genus of the subfamily Caputanurininae, by the characters listed in Table 1. Caputanurina intermedia Najt & Weiner, 1992 exhibits intermediate characters between the two genera, which are closely related.
Etymology. After the name of the type locality, the Khualaza mountain. Description. Holotype: 0.70 mm (female adult); paratypes: 0.60-0.70 mm (females), 0.45 (male RU032/5) to 0.61-0.62 mm (males juvenile). Habitus typical for the genus Leenurina. Abdominal tergum VI small, not hidden under V. Color in alcohol very light blue with blue-black 2+2 ocelli. Integument very strongly granulated dorsally, with tertiary granulation arranged in rather small and smooth subhexagonal areas encircled by 5 to 9 secondary granules, underlined by strong reticulations, and grouped as large plates on head (Figs 6C, H), on thorax II-III and on abdomen I to V (Fig. 6D). Two parallel lines of secondary granules along the axis from posterior part of head to abdominal tergum IV. Thoracic tergum I fused with head, sternum normal.
Antennae shorter than head. Antennal segment I with 7 chaetae, antennal segment II with 12 chaetae. Sensory organ on antennal segment III consisting of two small sensilla bent in the same direction, two almost equal, subcylindrical guard sensilla and a small ventral microsensillum. Antennal segment IV with 6 thick subcylindrical sensilla, a microsensillum, a subapical organite and a simple apical vesicle (Figs 1B, C).
Two ocelli per side, a little larger than surrounding integument granulation, indicated by blue-black pigment patches, but not distinct from surrounding secondary granules under microscopic examination. Postantennal organ slightly oval, about three times longer and two times broader than ocellus A, with 9-10 vesicles (Figs 1A, D). Buccal cone typical for the genus. Labrum truncated, labral chaetotaxy: 4/2,3,5,2, with prelabral chaetae as 2 axial and 2 lateral; the later assigned here to labrum might be as well lateral labial chaetae. Labium short, with 4 basal (E, F, G, f ), 3 distal (A, C, D) and 3 lateral chaetae; papillated chaeta L absent; 2+2 hyaline vesicles arranged one above the other between chaetae A and C (x papillae of Deharveng 1983) (Fig. 1E). Mandible with three small apical teeth and two strong basal ones. Maxilla with two lamellae (each with two apical teeth) and capitulum denticulate with minute teeth (Fig. 1F).
Dorsal chaetotaxy as on Fig. 1A, with thin short pointed ordinary chaetae and long thin s-chaetae, 4-5 times longer than ordinary chaetae. Some asymmetry observed. Ocular area with 3 chaetae. One lateral chaeta (Fig. 1A) located on what could be the subcoxa 1. Dorso-lateral chaetae of thoracic terga II and III in two groups (p6 shift posteriorly far from the s-chaeta, Fig. 1A). Formula of s-chaetae per half tergum: 022/11111; s-microchaeta present on thoracic tergum II, close and anterior to the lateral s-chaeta; s-chaeta on abdominal tergum IV almost as long as on abdominal terga II and III. From thoracic tergum II to abdominal tergum IV, 3 chaetae between the axis and the proximal s-chaeta: a1, p1 and a chaeta moving from a "p2" (usually on thoracic tergum II to abdominal tergum II) to a "p3" position (usually on abdominal tergum III-IV), with variation from one specimen and sometimes one side to the other. Thoracic sterna without chaetae. Chaetotaxy of abdominal sterna I-VI as in Fig. 1H. Lateral anal valves with two, upper valve with three hr-chaetae.
Etymology. The new species is dedicated to Professor R. Jacek Pomorski, the eminent taxonomist of Collembola and our friend, who left us in 2010.
Description. Holotype: 0.92 mm (female adult); paratypes: 0.84 mm (female), 0.6-0.9 mm (female juvenile), 0.58 mm (juvenile). Habitus typical for the genus Leenurina. Abdominal tergum VI small, sometimes hidden under V ( Fig. 2A). Color in alcohol white with 3+3 blue-black ocelli. Integument very strongly granulated dorsally, with tertiary granulation arranged in large smooth plates fringed with lines of strong secondary granules (Figs 2A, B, 6E, F, I). Well marked underlying small hexagonal reticulations (Fig. 5), each reticulation mesh connected with two or three secondary granules. Secondary granules rounded, the lateral ones very large. Two parallel lines of secondary granules along the axis from posterior part of head to abdominal tergum IV. Thoracic tergum I fused with head, sternum normal.
Antennae shorter than head. Antennal segment I with 7 chaetae, antennal segment II with 12 chaetae. Sensory organ on antennal segment III consisting of two small sensilla bent in the same direction, two almost equal, subcylindrical guard sensilla and a small ventral microsensillum. Antennal segment IV with 6 thick subcylindrical sensilla, a microsensillum, a subapical organite and a very slightly bilobed apical vesicle (Figs 3A, B).
Dorsal chaetotaxy as on Fig. 2, with short thin pointed ordinary chaetae and long thin s-chaetae, 3-5 times longer than ordinary chaetae. Some asymmetry observed. Ocular area with 3 (or 4 chaetae, probably as a result of a shift of a dorsal cephalic chaeta towards ocular area). One lateral chaeta on what could be the poorly individualized lateral part of thoracic tergum I (Fig. 2B), and another ventro-lateral chaeta on subcoxa 1. Dorso-lateral chaetae of thoracic terga II and III in one group (p6 close to s-chaeta, Fig. 2B).   Formula of s-chaetae per half tergum: 022/11111; s-microchaeta present on thoracic tergum II, close and anterior to the lateral s-chaeta; s-chaetae slighly thicker and shorter on abdominal tergum IV than on other terga. From thoracic tergum II to abdominal tergum III, 3 chaetae present between the axis and the proximal s-chaeta: a1, p1 and a chaeta in a "p2" position on thoracic tergum II-III and usually a "p3" position abdominal terga I-III. Abdominal tergum IV with only 2+2 chaetae between the axis and the proximal s-chaeta (a1, p1). Some specimens slightly depart from this pattern on details: one specimen with 4 chaetae present between the axis and the proximal s-chaeta on abdominal tergum I (a1, p1 and 2 other chaetae in row p) ; one specimen with 2 chaetae present between the axis and the proximal s-chaeta on abdominal tergum I (a1 and p1); one specimen with an additional chaeta antero-internal and close to the s-chaeta on abdominal tergum IV.
Discussion. Dorsal chaetotaxy of both described species exhibits some variability and frequent asymmetries. The four species of Leenurina are closely related, but easily distinguished on a combination of characters including eye number, pigmentation, leg and dorsal chaetotaxy ( Table 2).