Sensiphorura tiunovi, Shveenkova, 2017

Shveenkova, Yulia B., 2017, New Collembolan species of the genera Sensiphorura Rusek, 1976 (Pachytullbergiidae) and Cephalachorutes Bedos & Deharveng, 1991 (Neanuridae) from Southern Vietnam, Zoosystema 39 (1), pp. 75-85 : 76-79

Sensiphorura tiunovi n. sp.

( Figs 1 , 2 ; Tables 1, 3, 4)

TYPE MATERIAL. — Holotype. ♀, Southern Vietnam, Province Dong Nai, Cat Tien National Park , 12.XII.2005, deciduous riparian forest of Dipterocarpus alatus Roxb. ex G.Don on a levee near the Dong Nay River , soil, c. 137 m a.s.l., Yu. Shveenkova leg., deposited in MSPU. Paratypes. 2♀, same data as holotype, but forest of Lagerstroemia calyculata Kurz , c. 149 m a.s.l. ; 2 ♀, same data as holotype, but collected in 2006, leg. A. Anichkin.

Other material. 1 juv., same data as holotype ; 1 juv., same data as holotype, but 18.XI.2005 ; 1 ♀, same data as holotype, but forest of Afzelia xylocarpa (Kurz) Craib , 17.XII.2005 ; 2 ♀, same data as holotype, but collected in 2006, leg. A. Anichkin. 1 paratype are deposited in MSPU, 3 paratypes are deposited in MNHN .

MATERIAL EXAMINED. — The material of S. marshalli Rusek, 1976 : three specimens from Canada, Vancouver Island , from thick spongy hemlock litter on top of plateau, 31.V.1983, A. Fjellberg leg. ; 1 paratype of S. oligoseta Bu, Potapov & Gao, 2013 : ♀, from South China, Hainan Province (western coast), Changjiang County, vicinity of Changhua town , Qizi Bay , sand beach, flotation of sand samples, 7.IV.2011, C. W. Huang, M. B. Potapov, N. A. Kuznetsova and Y. Bu. leg. (deposited in MSPU) .

DIAGNOSIS. — Apical vesicle small and globular. Ventral AIIIO consisting of one large sensory club, one sensory rod, 3 long papillae and 3 protecting chaetae. Sensilla s present on Th. II-III. Lateral microsensilla ms present only on Th. II. Abd. I without a2 chaetae. M3 chaetae present on Abd. IV (only adult specimens) and a2 chaetae on Abd. II-III (last character variable among juveniles and adult specimen too). Sensilla on body: p3 on Th. II-III and Abd. I differentiating as slightly thickened sensilla; lanceolate sensilla present on abdomen dorsally (p3, Abd. II-V; p5, Abd. II-V; p5 on Abd. I varies - may be as chaeta ore as lanceolate sensilla, a0, Abd. VI); and 1+ 1 on Abd. V ventrally. Lower subcoxa I-III with 0, 2 + 1s, 2+ 1s (juveniles with 0, 1 + 1s, 1 + 1s) chaetae.

ETYMOLOGY. — The species is named in honor of Alexey Tiunov coordinating studies of soil fauna by Russian group in tropical forests of Cat Tien National Park, exploring the functional aspects of soil ecosystem.

DESCRIPTION

General

Holotype length 510 µm, color white, without pigmentation. Body shape cylindrical, granulation of integument very fine and uniform. Pseudocelli not visible. PAO usually consists of 9 vesicles (varies from 8 to 12) lying in two parallel rows, with 4 chaetae behind them ( Fig. 1A ). Anal spines short, set on small papillae.

Antennae

Antennae about as long as head or slightly shorter ( Fig. 1A ). Antennal segments III and IV almost fused, ventro-medial division more or less distinct ( Fig. 2 A-D). Apical part of antennae with 14 blunt sensilla: 2 short and thick on dorsal side, and 12 long and slim, five lateral ( Fig. 2D ) and seven medial ( Fig. 2C ) ones. Apical vesicle small and globular. Two microsensilla and small subapical organite present on apical part of antennae. Dorso-lateral antennal organ III as in Onychiuridae Lubbock, 1867 ( Fig. 2B, D, F ). It consists of one large sensory club, one sensory rod, 4 (5) long cuticular papillae (one of papillae often strongly bifurcate making expression of additional papilla, although only 4 papilla basements always observed) and 3 protecting chaetae. Similar structure (ventral AIIIO, consisting of one large sensory club, one sensory rod, 3 long papillae and 3 protecting chaetae) present ventrally ( Fig. 2A, D, G ). Ventral part of antennae have hillock formation of cuticle (tubercles) with 1-3 chaetae, which form a semicircle near ventral antennal organ ( Fig. 2A ). Ant. I and Ant. II with 7 and 11 chaetae, respectively.

Mouthparts

Mouthparts well-developed. Labium generally as in S. marshalli ( Fjellberg 1999: fig. 41) with 4 papilla (A-D), 2 long guard chaetae (b3, b4), 3 short guard chaetae (a1, b1, b2 – very small and reduced); 3 small hypostomal and 3 proximal chaetae are present ( Fig. 1D ). The basomedian and basolateral fields has 4 and 5 chaetae, respectively. Mandibles and maxilla as in S. marshalli .

Chaetotaxy

Head with chaetae a0 and c0, without d0. Dorsal chaetotaxy with frequent asymmetries ( Fig. 1A ). Juveniles with incomplete composition of chaetae: dorsal chaetae p1 on Abd. I-IV, m2 on Th. II-III, a2 on Abd. II-III and some other chaetae usually absent ( Table 4). The full composition of the chaetae (so-called chaetom pattern) more commonly found in adult specimens (see Table 1). Sensilla s present on Th. II-III. Lateral microsensilla ms present only on Th. II. Chaetotaxy of Abd. VI as on Figure 1A. A 0 is sensilla, it is as long as a1 and a2 chaetae. Ventral chaetotaxy as on Fig. 1B, C . Four rows of chaetae on Abd. IV. VT with 4 + 4 proximal chaetae and 1 +1 on the basis. 1 +1 sensilla present on Abd. V ventrally.

Legs

Upper subcoxa I-III with 1, 2, 2 chaetae respectively. Lower subcoxa I-III with 0, 2+ 1s, 2 +1s chaetae (juveniles with 0, 1+ 1s, 1 + 1s chaetae). Tibiotarsus with 11, 11, 10 (rarely 11) chaetae on leg I, II, III, respectively ( Fig. 2E ), without empodial appendage, claw without teeth.

REMARKS

The new species belongs to genus Sensiphorura due to two antennal sensory organs (on Ant. III-IV), high number of sensilla on apical part of antennae, simple vesicles of PAO arranged in two rows, reduced structure of labium, and missing visible pseudocelli. Ventral antennal sensory organ is unique feature of the genus.

Sensiphorura tiunovi n. sp. differs from other Sensiphorura spp. ( S. marshalli and S. oligoseta ) by the absence of microsensilla on thorax III (this character was verified and clearly seen on all 10 individuals). Microsensilla on thorax II present as in other species of the genus. New species differs from S. marshalli also with small apical sensory club, absence of a2 chaetae on Abd. I (in all specimens), unlike sensilla-pattern on body (differentiation of p3, p5 as chaeta or sensilla). Contrary to S. oligoseta , the new species has m3 chaetae on Abd. IV and a2 chaetae on Abd. II-III (last character variable among adult specimen too).

Chaetom of all species of Sensiphorura is age dependent and is often asymmetrical ( Table 4). In earlier age instars some chaetae may be absent: m2 on Th. II-III, and m3 on Abd. IV; a2 on Abd. II-III, p1 on Abd. I-IV, lateral chaetae on Abd. I. Chaetae on lower subcoxa are also unstable: adult have 0, 2 + 1s, 2 + 1s; juveniles - 0, 1 + 1s, 1 + 1s chaetae. P5 on Abd. I may be chaeta or lanceolate sensilla, it varies too.

After original description, S. oligoseta has only 11 slim antennal sensilla and 11 chaetae on Ti III (vs 12 and 10, in new species, respectively). Some variation probably exists in S. oligoseta : we observed one paratype of S. oligoseta , in which number of antennal sensilla and tibiotarsal distal chaeta on the third legs were the same as in new species (12 and 10). Material of S. marshalli examined by us also show 10 chaetae on Ti of third legs. By contrast, two specimens of Sensiphorura tiunovi n. sp. have increased number of chaetae on Ti III (11 +11 and 10 + 11 on left+ right third legs). So we are not including these features in differences between S. oligoseta and new species.

Different numbers of guard chaetae of dorso-lateral AIIIO (5, 4 and 3) were given for S. marshalli , S. oligoseta and S. tiunovi n. sp., respectively. In fact, this difference is explained by different terminology which was used in first descriptions. The chaetae positioned at base of papilla are included to this group by us ( Fig. 2F ), as common in Onychiuroidea ( Pomorski 1998; Weiner & Najt 1999).

Figures

FIG. 1. — Sensiphorura tiunovi n. sp.: A, dorsal chaetotaxy (by a dotted line chaetae on subcoxa and lateral chaetae; marked in circle:p5 on Abd.I, a2 on Abd.II-III, m3 on Abd. IV); B, ventral chaetotaxy of head; C, ventral chaetotaxy of abdomen (lateral chaetae by a dotted line); D, labium. Abbreviations: see Material and methods. Scale bars: A-C, 0.05 mm; D, 0.01 mm.

FIG. 2. — Sensiphorura tiunovi n. sp.: A-D, antennae, ventral (A), dorsal (B), medial (C), and lateral (D) views; E, tibiotarsus, two different views (chaetae by a dotted line absent on Ti of third legs); F, dorso-lateral AIIIO; G, ventral AIIIO (1-3 – protected chaetae).Abbreviations: or, organite; ms, microsensilla. Scale bars: A-D, 0.025 mm; E-G, 0.01 mm.