Tantulonychiurus amuricus, Babenko, Anatoly B., Chimitova, Ayuna B. & Stebaeva, Sophya K., 2011

Babenko, Anatoly B., Chimitova, Ayuna B. & Stebaeva, Sophya K., 2011, New Palaearctic species of the tribe Thalassaphorurini Pomorski, 1998 (Collembola, Onychiuridae), ZooKeys 126, pp. 1-38 : 13-14

Sensillonychiurus amuricus sp. n. Figs 24-31

Material.

Holotype ♀, Russia, Asiatic part, Khabarovsk suburbs, right bank of Amur river [48°33'N, 135°01'E], upper part of sandy beach (flotation), 26 iv 2010, M. Potapov leg (MSPU).

Paratypes 3 ♀, 4 ♂ and 1 juv., same data as holotype (MSPU).

Description.

Colour white. Size of mature specimens 0.62-0.72 mm. Body slender and elongated. Antennae about as long as head, antennal area not clearly demarcated. Ant.4 with a subapical organite, two distinct thickened sensilla, and a subbasal microsensillum set well above proximal row of setae (Fig. 25). Ant.3 organ consisting of 5 papillae, 2 sensory rods, 2 smooth sensory clubs (Figs 26-27), 4 guard setae, and a lateral microsensillum (Fig. 25). Ant.1 and 2 usually with 8 and 13(14) setae, respectively. PAO with 6-7 composed vesicles (Fig. 28). Labrum with 7 setae and 2 prelabral ones (2/3-4). Apical part of labium with thick terminal setae on papillae A and C (AC - type), 7 long guard setae [b3-4, d3-4, e1-3] and 4 spiniform ones [a1, b1-2 and d2] set on low papillae, a1 clearly longer and thicker than b1. Proximal part of labium as usual, with 6 setae, basal fields (mentum and submentum) with 4 and 5 setae. Maxillary palp simple, with 2 sublobal setae.

Pseudocellar formula (pso) as follows, dorsal: 32/133/33343, ventral: 1/000/0000, parapseudocelli (psx) invisible. Each upper subcoxa with one pso. Localization of pso as in Fig. 24. Granulation rather fine and uniform, without areas of clearly enlarged granules. Dorsal chaetotaxy almost symmetrical, setae smooth and clearly differentiated, especially on last abdominal terga, differences between macro- and microsetae in anterior parts of body not so pronounced but visible: macrosetae more straight and blunt, microsetae curved and pointed. Dorsal sensilla distinct, flame-like, 1/011/221111 in number (Fig. 24), ventral ones (2/000/0001) slightly thickened and sometimes hard to detect, sensillum on coxae of Lg.3 distinct. Th.1 with 6+6 setae. Lateral microsensilla present only on Th.2. Unpaired dorsal seta d0 on head absent, Abd.4 with m0 and p0, Abd.5 with p0, Abd.6 with one axial macroseta (Fig. 24). Thoracic sterna without setae along linea ventralis. Abd.3 sternum unclearly divided, anterior subsegment without setae. Furca reduced to a small area of fine granulation situated at contact with border between Abd.3-4 sterna, with 2+2 small posterior setae arranged in two rows, manubrial area with 4+4 setae set in two rows. Ventral tube with 6+6 distal setae, proximal ones at corpus base absent. Upper subcoxae usually with 3-4-4, tibiotarsi with 17-17-16, setae: distal rows with 9 setae (2 T-setae absent), row B with 7-7-6 setae, setae M absent but Y present (Figs 29-30). Unguis simple, with neither inner nor lateral tooth, unguiculus with an indistinct basal lamella, shorter than unguis (ca 0.7 U3).Anal spines short (0.7-0.75 U3) and thin, set without papillae (Fig. 31).

Affinities.

The same structure of AO (five papillae and four guard setae) as in Sensillonychiurus amuricus sp. n. is only known in two species of the genus, Sensillonychiurus mirus sp. n. and Sensillonychiurus vitimicus sp. n. All these species which are characterized by only a weak reduction of AO with a full number of papillae and 4 guard setae also show the highest number of setae (9) in the distal tibiotarsal whorl. Both can easily be distinguished from Sensillonychiurus amuricus sp. n. in having a different type of the labium (ABC versus AC in Sensillonychiurus amuricus sp. n.) and four prelabral setae ( Sensillonychiurus amuricus sp. n. possesses only two prelabral setae, which occurs more commonly in the genus). Apart from this, Sensillonychiurus amuricus sp. n. is the largest congener.

Two other species of the genus, Sensillonychiurus virginis and Sensillonychiurus geminus , are characterized by the most complete set of tibiotarsal setae (17-17-16) but against the background of a pronounced reduction of AO.

Etymology.

The new species was named after its terra typica.

Distribution.

Known only from the type locality.