Heteroisotoma sinorossica, Jie, Ding, Potapov, Mikhail & Sokolova, Elena, 2011

Jie, Ding, Potapov, Mikhail & Sokolova, Elena, 2011, Further study on the labial palp in the Isotomidae (Collembola) with reference to the genus Heteroisotoma Stach, Zootaxa 2991, pp. 49-61 : 51-55

Heteroisotoma sinorossica sp. nov.

Figs 2 , 6–25

Type material. Holotype: male, China, Ji Lin province, Changbai Mountain, July 2009, collection number C9593, leg. Chen Jianxiu and Zhang Feng. Paratypes: 5 females, same data as for holotype (deposited in NJU) and 5 specimens labelled as: Russia (Far East), South Primorye, Khasansky area, near Barabash, oak wood on slopes, ~ 200-400 m alt., litter, 27.ix.2004, leg. M. Potapov (below as M.P.) (deposited in MSPU).

Other material. North Korea: Kangwon-do Province, Kymgang-san, river valley, downstream from waterfall Kurjong-pho, shrubs, N Korea 18.vii.1985, leg. A. Szeptycki (K-85-56); Yanggang-do Province, Road from Samdzijon to Hjesan, ~ 18 km from od Samdzijon, wood with spruce, pine-tree, and hazel, 1260 m alt., damp place, 2.vii ..1985, leg. A. Szeptycki (K-85-31); Hamgyong-namdo Province, not far from Machon-riong, rich deciduous forest (oak, maple, lime-tree, hazel), 28.v.1987, leg. A. Szeptycki (K-87-21). The Korean material is kept in ISEA.

Russia (Far East): South Primorye, Khasansky area, ~ 15 km S Kraskino, Mramorny Cape, oak wood, deep moist litter on bottom of ravine, 28.ix.2004, leg. M.P.; ibidem, sea shore, soil under reed, 28.ix.2004, leg. M.P.; ibidem, sea shore, rich soil under Leguminosae, 28.ix.2004, leg. M.P.;, Reserve " Kedrovaya Pad' ", Valley of Kedrovaya River, mixed forest, litter under pine and spruce. 29.ix.2004, leg. M.P.; Shkotovsky area, Livadiysky Range, Khualaza Mt., below the top (RU-017), litter, 19.ix.2004, leg. A. Bedos & L. Deharveng; ibidem, near the bottom of Khualaza Mt., moist mosses on rocks in deep crevice, 2.x.2004, leg. M.P.; Livadiysky Range, Pidan Mt., litter under pine ( Pinus koraiensis ), 20.ix.2004, leg. M.P.; South Primorye, middle flow of Bikin River (at inflow of Amba River), mixed forest with pine, litter, N 46,69949 E 135,77142, 20.ix.2009, leg. O. Smirnova; Khabarovsky Krai, nearby Khabarovsk, Bol'shoy Khekhtsyr, ~ 10 km N Korfovsky, mixed forest, 28.vi.2007, leg. E. Sokolova.

Description. Body size up to 1.2 mm. Body shape as common for the family, head large. Abd. V and VI separated, with a fold and clear break in setal cover. Pure white, some specimens with scattered granules of black pigment ( Fig. 25 ). Integument smooth, without visible granulation.

No ocelli. PAO long and usually subdivided into lobes ( Fig. 21 ), upper and lower ends narrowed, often bilobed, 1.7–2.6 as long as claw III. Ant. I ( Fig. 14 ) on ventral side with two long sensilla ( Fig. 19 c) and from two to three short ones ( Fig. 19 a) in apical position. Ant. II ( Fig. 15 ) normally with 5 sensilla ( Fig. 19 c). Ant. III organ normal, with a pair of blunt rods in a groove ( Figs 16 and 19 d). Ant. IV ( Figs 17–18 ) with several curved sensilla of different thickness ( Figs 19 a,b), apical bulb hardly developed. Subapical pin seta absent, subapical organite elliptic, often "opened" (resulting probably from fixation), subapical microsensillum as common for the family ( Fig. 23 ). Labrum with 4/554 slender setae, apical edge with 4 sharp ridges ( Fig. 20 ) and a composite ventral ciliation. Central part of fronto-clypeal field with about ten setae. Maxillary outer lobe with trifurcate palp and 4 sublobal setae ( Fig. 24 ). Labial palp with all apical papillae (A–E) and 16 guards, 4 proximal setae; small guard e7 present (rarely absent on one side, see: Remarks) at distance from papilla E, terminal seta of the papillae not shorter than guards. Lateral process (l.p.) at papilla E finger-like. Medial process (m.p.) of the same shape present between papilla A and first proximal seta. Papillae B and D with B' and D' processes on inner side which vary depending on specimen, from small pimples ( Fig. 2 ) to distinct lobes ( Fig. 1 ). Hypostomal seta H 1.5 times longer than h1 and h2. Basal fields of labium with 4 median and 5 lateral setae. With 4–5 + 4–5 postlabial setae along ventral line. Mandibles normal. Maxillae with 3-toothed capitulum and 6 unmodified lamellae ( Fig. 22 ), without long denticles, not projecting beyond tip of capitulum.

Legs long. Tibiotarsi with 8 acuminate distal setae. Claws as common for the genus ( Fig. 12 ), with strong inner, tiny (nearly invisible) outer and two lateral teeth, unguiculus with wide lamella and inner tooth. Lower subcoxa of leg I with 2–4 outer setae. Ventral tube with 8–10 + 8–10 anterior setae, 4–5 + 4–5 lateral and 10–14 posterior setae. Retinaculum with 4+4 teeth and 6–7 setae ( Fig. 9 ). No ventral setae on thorax. Ventroapical thickening of manubrium multispinose, normally with several (4–6) strong and often with some smaller teeth ( Fig. 13 ). Ventroapical area of manubrium with 2 + 2 spines one of which swollen at base ( Fig. 13 ). Dens with many anterior and few posterior (9-12) setae. 8 (sometimes 7 or 9) setae of inner row of dens modified to pointed spines, swollen at base and elongated in distal part, 2 basal spines arranged closer to anterior part. Spines of manubrium and dens with big glands under bases ( Figs 8, 11, 13 ). Mucro short, tridentate, no seta ( Fig. 10 ). Reproductive males without special modification.

Macrochaetotaxy as common for the genus: 3,3, 3,3 in number on Abd. I–IV. Under high magnification macrosetae slightly serrated (hardly visible in some specimens), especially on last abdominal segments. General shape of macrosetae on last two abdominal segments somewhat as in Entomobryidae : expanded at distal half. On Abd. V macrosetae 1.2–1.3 times as long as tergite length. Sensillar chaetotaxy complex since some common setae and macrosetae appear to be sensilla-like ("pseudosensilla"). Normal macrosensilla as 5,4-5/4,4,4,4,6(7) in number, slightly thickened, blunt at apex. Th. II with two medium-sized and one long accp-s and two short al-s, Th. III with three medium-sized and one long (often absent) accp-s and one short al-s. Medial macrosetae of Th. II and III slen- der, filament-like, which appear similar to trichobothria. Abd. I–IV each with three medium-sized (longer on more posterior segments) and one short s in more lateral position. Three medial sensilla normally in p-row, one or two often in more anterior position, a lateral sensillum well in front of p-row on Abd. I-II and within p-row on Abd. III– IV. Abd. V with two as-s and four accp-s. In accp-s two long and two short. Sensilla accp-5 possibly present (masked by cover of "pseudosensilla"). Microsensilla big, 1,1/1,1,1, in front of p-row on Abd I,II and normally in p-row on Abd. III. Number of p-setae between accp-s and ms on Abd. I-IV as: 3s1s1s, 4s1s2s, 4s1s1s1ms1s, ½s2s1s1s (with slight variation) ( Figs 6-7 ).

Remarks. The species differs distinctly from other species of the genus by the presence of a row of spines along inner side of dens and in having only two (vs. four) spines in ventroapical group on manubrium. The PAO being subdivided into several lobes is shared with H. carpenteri and the absence of eyes with H. stebajevae . In new species, the considerable portion of common setae on dorsal side of Abd. III–VI thin and tubular giving an impression of dense cover of thin sensilla. In most specimens the real number of typical sensilla is masked by these "pseudosensilla" (notated as s' on figure) which only slightly differ from normal sensilla in width and form of tip.

The specimens from Bikin have no guard e7 on labium. Since presence of this guard is not stable in other populations (may be absent on one side) we assume Bikin specimens to belong to H.sinorossica sp. nov., too.

Etymology. The species is named after its distribution. China and Russia were two countries where the species had been found first.

Distribution and ecology. Probably widely distributed in coastal ridges of NE China, North Korea, and South of Far East of Russia. In moist and rich forest litter, rather eurytopic.

Figures

FIGURES 1 – 5. Labial palp in Heteroisotoma spp.: 1, H. carpenteri; 2, H. sinorossica sp. nov.; 3, H. dilatosetosa; 4, H. stebajevae; 5, H. jacutica; A, B, C, D, E: papillae, m. p., l. p.: medial and lateral processes, B', D': additional processes, e 7: guard e 7, prx 1: proximal seta 1.

FIGURES 6, 7. Heteroisotoma sinorossica sp. nov.: 6, chaetotaxy of dorsal side of Abd. IV-VI; 7, macrosetae, sensillae and prow of common setae on body tergites; s, accp, as: macrosensillum, ms: microsensillum, s': " pseudosensillum ", Mac-s: filament-like macroseta.

FIGURES 8 – 13. Heteroisotoma sinorossica sp. nov.: 8, posterior side of dens, basal half; 9, retinaculum; 10, mucro; 11, furca, anterior view; 12, apical part of leg III (outer edge of claw also shown); 13, ventroapical area of manubrium.

FIGURES 14 – 25. Heteroisotoma sinorossica sp. nov.: 14 – 17, antennal segments, dorsal view, Ant. I, II, III, IV, respectively; 18, Ant. IV, ventral view; 19, various shape of sensilla on antenna; 20, apical ridges of labrum; 21, PAO; 22, maxillary head, dorsal view; 23, tip of antenna; 24, maxillary outer lobe; 25, habitus of darker specimen.