Uralaphorura varicellata, Babenko, Anatoly, 2009

Babenko, Anatoly, 2009, Two new species of the genus Uralaphorura Martynova, 1978 (Collembola: Onychiuridae) from Siberia, Zootaxa 2108, pp. 37-44 : 38-41

Uralaphorura varicellata sp. nov.

Figs 1–8

Description. Colour white. Size 1.5–1.6 mm, minimal length of mature specimens about 1.2 mm. Body rather short and broad. Granulation fine and uniform, without differentiated fields of coarser granules.

Microsensillum on Ant.IV set between first and second whorls of proximal setae ( Fig. 7 ), subapical organite present. Ant.III organ with 4 papillae, two sensory rods, two granulated clubs, bent and subequal, 5 guard setae, and lateral microsensillum ( Figs 7, 7 a). Ant.I–II with 9 and 17–18 setae.

PAO usually with 18 (14–20) simple or slightly bilobed vesicles ( Fig. 6 ). Labrum with 4 prelabral and 9 labral setae. Labium with thick terminal seta only on papilla A, 7 long guards and 6 proximal setae present, basal fields of labium with 4+6 setae. Maxillary palp simple with two sublobal hairs.

Number and position of dorsal pseudocelli variable ( Fig. 1 ) and often asymmetric. Dorsal pseudocellar formula (holotype): 3,2/1,4,3–4/4–5,5–6,4,5,3, for all specimens: 3,2–5/1–2,4–6,4–6/4–6,4–10,4–7,4–8,3–4. Number of ventral pseudocelli more stable: 1(lateral)/000/0112 ( Fig. 2 ), but rarely some pseudocelli present in unusual position ( Fig. 3 ). Each subcoxa with 2–3 pso. Pseudocellar formula of I instar (Th.I with 1+1 setae) as following: dorsal pso 22/022/44433, ventral pso 1(lateral)/000/0000 ( Figs. 4 ). Third pso on antennal base, pso on Th.I, third pso on Th.II–III, and at least some ventral abdominal pso present from II instar (Th.I with 4+4 setae in a row). Instar III with more than one pso on subcoxae and complete number of ventral pso on abdomen. Parapseudocelli (psx) as follows: 2/000/2100, on head one psx in anterior (sublabial) position, other psx median (in usual position of v-pso). Inner side of each femur and ventro-posterior side of each subcoxa with one psx ( Fig. 8 ), two subapical psx (outer and inner) present on Ant.III ( Fig. 7 ).

Dorsal chaetotaxy partly plurichaetotic and often asymmetric ( Fig.1 ), most setae blunt. Macrochaetae distinct, especially on abdominal tip. Th.II–III with lateral microsensilla. Head with seta d0 present. Unpaired median setae p0 on terga of Abd.IV–V present or absent, Abd.VI always with two dorsal axial setae. Thoracic sterna without setae along linea ventralis, ventral chaetotaxy of abdomen as in Fig. 2 . Furcal remnant as small finely granulated area with posterior row of 4 setulae ( Figs 2, 5 ). Male organ absent. Ventral tube with 7–11 setae on each lateral flap and with 1+1 proximal setae on corpus.

Each subcoxa usually with 4 setae. Tibiotarsi in adults with 20–23(24) setae (all four T-setae present, 7 setae in A- whorl, 7(6) in B- whorl, 1–3(4) setae in C- whorl, setae M and Y). Setae A1 on all tibiotarsi, B4–5 on Ti.I–II and B5 on Ti.III are longer than others but not clavate. Unguis with small inner tooth, lateral teeth absent, unguiculus without basal lamella, slightly longer than inner edge of unguis. Anal spines present, papillae very low.

Type material. Holotype: female, Russia, Yakutia (Sakha Republic), Suntar-Khayata Mt. Range, upper current of Kyubyume River (63°13'N, 139°32'E), 2150 m alt., wet ravine on terrace, 1.viii.2002, O. Makarova leg., in MSPU; paratypes: 4 females, 2 males, and 1 juvenile (I instar), same data as holotype; 3 females, 6 males, same region, 1800–1900 m alt., mosses along springs, 15.vii.2002; 5 females, 6 males, and 4 juvenile (II and III instars), same region, 1800 m alt., willow bushes with lichen cover, 9.vii.2002; 1 female, same region, 1800 m alt., Dryas association, 9.vii.2002; 3 females, 6 males, same region, 1950 m alt., snowfield, 1.viii.2002. O. Makarova leg., in MSPU.

Affinities. U. varicellata sp. n. is an unusual species for the genus as it is characterised by an increased and unstable number of dorsal pseudocelli, a replacement of some ventral parapseudocelli on head and abdomen by true pseudocelli, and by the presence of psx ventro-anteriorly on head and on posterior parts of subcoxae. All other morphological characteristics of the species (structure of labrum and labium, furca remnant, AO, PAO, mutual position of antennal pso, the absence of v-pseudocelli on head and axial setae on thoracic sterna, 2 psx and only one seta on VT base etc.) conform with the other known species of the genus.

Remarks. In a collection from the European part of Russia (Archangelsk District) there is a single immature specimen (II instar) which is inseparable from juveniles of U. varicellata sp. nov. having the same number of dorsal and ventral pseudocelli (dorsal pso: 32/133/44433, ventral pso: 1(lateral)/000/0?11). It could be conspecific to U. varicellata sp. nov. even if the collecting localities are separated by more than 4000 km, but more probably it indicates the presence of more than one Uralaphorura species with increased number of pseudocelli in Eurasia. Unfortunately a second sampling in the same site did not reveal additional material.

In the above description psx in uncommon positions are mentioned, viz. on ventro-posterior side of each subcoxa ( Fig. 8 ) and distally on Ant.III ( Fig. 7 ). These characters are probably not unique although not mentioned in literature before. The former is very hard to detect due to its position, the latter (antennal psx) has been seen in many species of various onychiurid tribes, for instance, Hymenaphorurini, Oligaphorurini, and Protaphorurini.

Etymology. The name reflects the most characteristic feature of the new species—inconstancy in number and position of dorsal pseudocelli.

Distribution. Known only from surroundings of the type locality (but see also remarks) where it is one of the most numerous onychiurids in various habitats between altitudes of 1700–2200 m.

Figures

FIGURES 1 – 5. Uralaphorura varicellata sp. nov.: 1, dorsal chaetotaxy (adult); 2, ventral chaetotaxy of abdomen (adult); 3, Abd. V – VI with unusual pair of ventral pso; 4, dorsal chaetotaxy (I instar); 5, ventral chaetotaxy of abdomen (I instar). Scales: 0.1 mm.

FIGURES 6 – 11. Uralaphorura varicellata sp. nov. (6 – 8) and U. yanensis sp. nov. (9 – 11): 6, 9, PAO and nearest pso, 7, Ant. III – IV, 7 a, AO, sensorial elements, 8, pso and psx on subcoxa of leg II; 10, AO, 10 a, sensorial elements; 11, chaetotaxy of right Ti. III. Scales: 6 – 7, 9 – 11: 0.01 mm, 8, 0.05 mm.