Oligaphorura duocellata, Bagnall, 1949
Babenko, Anatoly B. & Fjellberg, Arne, 2015, Subdivision of the tribe Oligaphorurini in the light of new and lesser known species from North-East Russia (Collembola, Onychiuridae, Onychiurinae), ZooKeys 488, pp. 47-75: 48-50
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Taxon classification Animalia Collembola Onychiuridae
Oligaphorura duocellata sp. n. Figs 10-16
Holotype ♂, Russia, Magadan District, upper reaches of Kolyma River, Bolshoi Annachag Mt. Range, field station “Aborigen” [61°56'N, 149°40'E], mosses on slope, 1400-1500 m alt., 27.vii.1979, leg. A. Fjellberg (MSPU).
Paratypes 1♂, 1♀, and 1 juvenile, same data as holotype (MSPU).
Colour white. Size of adults 1.2-1.3 mm. Body slender and elongated. Antennae slightly shorter than head, club-like with Ant.4 clearly wider than Ant.3. Subapical organite on Ant.4 peg-like, basal microsensillum set on level with proximal whorl of setae. AO consisting of 5 long papillae, 2 sensory rods, 2 granulated sensory clubs clearly differing in shape (Fig. 12), 5 guard setae and a lateral microsensillum. Ant.1 and 2 usually with 8 and 14 (15) setae, respectively. PAO about as long as nearest pso, usually with 3 elongated lobes (Fig. 11). Labrum with 9 setae and 4 prelabrals. Apical part of labium with thick terminal setae on papillae A and C (AC-type), terminal setae on all papillae rather short (Fig. 13), 7 long, usual 4 spiniform guard setae and 6 proximal setae present. Basal fields of labium (mentum and submentum) with 4 and 5 setae, hypostomal complex of usual shape. Maxillary palp simple, with 2 sublobal setae.
Pseudocellar formulas (pso) as follows, dorsal: 32/(1)233/33343, ventral: 11/000/1111(2), parapseudocelli (psx) hardly visible (probably due to long preservation), but psx on unpaired anal lobe present. Upper subcoxae with 2-(2)3-3 pso, one dorsal and 1-2 ventral. Localization of dorsal pso as in Fig. 10, submedial pso on Abd.4 set far apart. Granulation fine and uniform, without areas of enlarged granules. Dorsal chaetotaxy more or less symmetrical, but with frequent variations even in axial parts of terga. Setae smooth and clearly differentiated only on abdominal tip: meso and macrosetae straight, thick and blunt, microsetae curved and pointed, sensory setae indistinct (Fig. 10). Th.1 with few setae, (3)4+4 as a rule, even in full grown specimens. Both Th.2 and 3 with lateral ms. All terga from Th.2 to Abd.3 with 3+3 axial microsetae as a rule. Setae p1 set clearly in forward position comparing with p2 setae on head and Th.2-Abd.3. Unpaired dorsal seta d0 on head absent, Abd.4 m1 setae fine and curved, much shorter than straight a1 and p1, Abd.6 with axial macroseta a0 almost subequal to a2 setae. Thoracic sterna of Th.2-3 without setae along ventral line. Furca reduced to a small area with fine granulation situated in some distance from anterior border of Abd.4, 2+2 setae arranged in 2 rows below furcal remnant are clearly shorter then surrounded ones and moved posteriorly (Fig. 16). In juveniles manubrial field with 3+3 setae between furcal remnant and q-setae (Fig. 15), adult with few additional setae in intermediate position (Fig. 16). Ventral tube with 7+7 distal setae and 1-2 proximal ones at base. Upper subcoxae usually with 3-4-(4)5 setae, tibiotarsi with more than 20-20-19 setae: distal whorl always with 11 setae (7 A and 4 T-setae), whorl B with 7-7-6 setae, setae M and variable C-whorl with one or two setae present. Unguis simple, with neither inner nor lateral teeth, unguiculus with wide basal lamella, clearly shorter than unguis (Fig. 14). Anal spines long and rather thin set without clear papillae.
Several uncommon features, like 2+2 pseudocelli and few setae on Th.1, the presence of pseudocelli on several abdominal sterna, the absence of setae on thoracic sterna, and a furcal remnant in the form of a finely granulated area with 4 small setae behind it, permit easy identification of the new species. In addition to Oligaphorura duocellata sp. n. nine known species of the tribe possess pseudocelli on several abdominal sterna. Three of them, Archaphorura serratotuberculata (Stach, 1933), Archaphorura alavensis Simón & Luciáñez, 1994, and Archaphorura marcuzzii (Cassagnau, 1968) are usually considered as representatives of the genus Archaphorura due to the absence of anal spines. The presence of ventral pso in the former species is uncertain as specimens from Moscow vicinity contrary to those from Poland (see Pomorski 1998) have only ventral psx on abdomen. The loss of anal spines also characterizes Oligaphorura humicola , Oligaphorura kremenitsai and Oligaphorura ambigua sp. n.
The only known species of the tribe with AS and pso on several abdominal sterna ( Micraphorura multiperforata (Gruia, 1973), Micraphorura uralica (Khanislamova, 1986), are within Micraphorura on the www.collembola.org or treated as Dimorphaphorura ( Dimorphaphorura olenae Weiner & Kaprus’, 2014). Micraphorura multiperforata is a unique species with dorsal pso multiplication, whereas Micraphorura uralica seems to be the most similar to Oligaphorura duocellata sp. n. having also more than 2 pso on subcoxae (a unique character) and no setae on thoracic sterna, a character which is known only for species from eastern parts of Asia and North America, i.e. Oligaphorura nuda (Fjellberg, 1987), Oligaphorura judithae (Weiner, 1994), Oligaphorura linderae (Weiner, 1994), Oligaphorura montana Weiner, 1994, Oligaphorura pseudomontana Sun & Wu, 2012, and Oligaphorura chankaensis Sun & Wu, 2012.
Named after the presence of 2+2 pso on Th.1, a character previously unknown for the tribe.
Known only from the type locality.
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