Rambutanura hunanensis Jiang & Dong, 2018

Dong, Ling, Yang, Yue-Li, Zhao, Yu-Yao, Wang, Yuan-Jun & Jiang, Ji-Gang, 2018, First record of the tropical genus Rambutanura (Collembola: Neanuridae: Neanurinae) in Palearctic, with description of a new species from China, Zootaxa 4378 (3), pp. 377-386 : 378-384

Rambutanura hunanensis Jiang & Dong sp. nov.

( Figures 1–14 , Tables 1–4)

Type material. Holotype female, Badagongshan National Nature Reserve , Sangzhi county, Hunan Province, China. Coordinates: 29° 47'8.25"N, 110°5'39.11"E, elevation 1395 meters. May 1, 2016. Collected by Ji-Gang Jiang, Ling Dong, Yuan-Jun Wang, Yue-Li Yang, Qing-Jing Zhao. Collection number as J20160501012 . Paratypes: 9 females and 3 males, 21 specimens in alcohol, the same data as holotype .

Etymology. The species name derived from the type locality: Hunan Province, China.

Description. General ( Figs 1–3 ). Body length (without antenna) 3.5–4.6 mm, holotype 4.5 mm. Cuticular granulations medium, tertiary granules absent, body without reticulations. Tubercles well developed on dorsal side of body. Body color red alive, terminal of antenna and claw light red ( Fig. 1 ), white in alcohol ( Fig. 2 ). Eyes 2+2, no pigment ( Fig. 3 ), anterior oculus not on tubercle Oc.

Chaetal morphology. Dorsal ordinary chaetae of 5 types: Ml, Mc, Mcc, me and mi. Macrochaetae Ml moderately long, thin, straight, narrowly sheathed, smooth and pointed at apex ( Fig. 6a–b ). Macrochaetae Mc morphologically similar to long macrochaetae, but shorter ( Fig. 6c ). Macrochaetae Mcc short, straight, sheathed, and slightly widened than Mc ( Fig. 6d ). Mesochaetae similar to ventral chaetae, thin, smooth, and pointed, with various length ( Fig. 6e–h ). Microchaetae shorter than mesochaetae, serrate with acuminate tip ( Fig. 6i ). s-chaetae of tergites thin, smooth, shorter than Mc and longer than Mcc ( Fig. 6j ).

Antenna. Antenna 4-segmented. Ant. I with 12–13 Chaetae. Ant. II with 11 Chaetae. Ant. III dorsally fused to Ant. IV. AOIII consists of 2 short rods, 1 ms and 2 longer sensory chaetae (sgd and sgv), sgd migrated distally on Ant. IV, each rod exposed in separate pit ( Figs 4, 6 ). Ant. IV plurichaetosis, dorsally with 8 sensilla, slender ichaeta, and minute capitate organite (or), apical bulb small, trilobed ( Fig. 5 ). 8 sensory chaetae weakly differentiated, slightly larger and shorter than that of “mou” ( Fig. 4 ). Ventral chaetotaxy of Ant. III–IV as in Fig. 5 and Table 3, ap with 9 bs and 4 miA, ca with 2 bs and 3 miA, cm with 3bs and 2 miA, cp plurichaetosis, with 3 miA. On ventral side of Ant. III, Vi, Vc, Ve respectively with 3,5,5 chaetae.

Mouthparts. Buccal cone short, labral sclerifications not ogival. Labrum chaetotaxy: 0/2, 2 ( Fig. 9 ). Labium with four basal, three distal, four lateral chaetae and 2 papillae x ( Fig. 10 ). Maxilla styliform ( Fig. 8 ). Mandible with 3 main teeth, the middle one subdivided into 2 teeth, so, mandible totally with 4 teeth ( Fig. 7 ).

Dorsal chaetotaxy and tubercles. Head with 8 tubercles ( Figs 2–3 and Table 1). Tubercle Cl with 6 chaetae: 2G+2F+2D; tubercle Af with 9 chaetae, Chaeta O present, Chaeta D migrated to tubercle Cl; each tubercle Di+De with 5 chaetae; tubercle Oc with 3 chaetae; tubercle Dl+L+So with 13–15 chaetae ( Fig. 3 and Table 1). All body Ml, Mc, Mcc and s smooth, mi dorsally weakly ciliated (observed under the lens of 40 times). Thorax. Thoracic dorsal tubercles complete ( Figs 2–3 ). Th. I with 3 tubercles, tubercle Di with 3 chaetae (2+s); tubercle De with 6 chaetae (3+3s); tubercle Dl with 4 chaetae (without s). Th. II with 4 tubercles, tubercle Di with 4 chaetae (3+s); tubercle De with 5 chaetae (4+s); tubercle Dl with 9 chaetae (6+2s+ms); tubercle L with 4 chaetae (without s). Th. III with 4 tubercles, tubercle Di with 4 chaetae (3+s); tubercle De with 5 chaetae (4+s); tubercle Dl with 7–8 chaetae (5–6+2s); tubercle L with 4 chaetae (without s) ( Fig. 3 and Table 2). Abdomen. Dorsum of Abd. I with 4 tubercles, tubercle Di with 3 chaetae (2+s); tubercle De with 4 chaetae (3+s); tubercle Dl with 2 chaetae (without s); tubercle L with 5 chaetae (3+2s) ( Fig. 11 ). Tubercles and chaetae arrangements of Abd. II–III as on Abd. I ( Fig. 11 ). Abd. IV with 4 tubercles, tubercle Di with 3 chaetae (2+s); tubercle De with 3 chaetae (2+s); tubercle Dl with 3 chaetae (without s); tubercle L with 8 (6+2s) or 9 (7+2s) chaetae. Abd. V with 2 tubercles, tubercle Di+De+Dl with 9 chaetae (7+2s); tubercle L with 15 chaetae (13+2s). Abd. VI bilobed, each side of Abd. VI with 1 tubercle, usually with 9 chaetae (rarely 8 or 10 chaetae) ( Figs 2–3 , 12 and Table 4). Strong cryptopygy.

Sensory chaetae formula on tubercle Di of Th. I–Abd. IV is 1,1,1/1,1,1,1. Sensory chaetae formula of tubercle De on Th. I–Abd. IV is 3,1,1/1,1,1,1. Sensory chaetae and ms formula on tubercle Dl of Th. I–Abd. IV as 0,2+ms, 2/0,0,0,0,0. Sensory chaetae formula on tubercle L of Abd. I–IV as 2,2,2,2 ( Fig. 3 and Table 4). Tubercle Di+De+Dl on Abd.V with 2 s-chaetae. Tubercle L on Abd.V with 2 s-chaetae too. Tubercles on Abd. VI without s chaetae ( Figs 3 , 12 ).

Ventral chaetotaxy. On head, groups Vea, Vem and Vep with 4,5,2 chaetae respectively ( Fig. 10 ). Group Vi on head with 5 chaetae ( Fig. 10 ). VT with 1 proximal and 5 (or 4) distal chaetae ( Fig. 14 ). On Abd III, furca rudimentary with 6–9 chaetae, and without microchaetae ( Fig. 14 ). On Abd IV, group Vei, Vec, Vel respectively with 1, 1, 3 chaetae ( Fig. 14 ). On Abd V, group Vl with 4 chaetae, chaeta L’ absent. Anal lobe with 24–25 chaetae and 3 mi.

Appendages. Unguis with an inner tooth and without lateral tooth. Chaeta M on tibiotarsus absent. Tibiotarsus of foreleg, midleg and hindleg, respectively with 18, 18, 17 chaetae. Chaetotaxy of legs, ventral tube and furcular remnant as in Figs 13–14 , Table 4.

Ecology. In leaves of Magnolia officinalis Rehder & Wilson at a small ditch near the road.

Remarks. The following characters of the new species: 2+2 depigmented eyes on head, colour of the body red when alive, without blue pigment, body tubercles developed, swelling, mandible with four teeth, maxilla styliform indicate that it is a member of the tribe Paleonurini Cassagnau, 1989 .

The presence of additional s-chaeta on tergites and 6 chaetae on cephalic tubercle Cl of the new species are similar to the species Digitanura quadrilobata Deharveng, 1987. However, the characters of tubercle Di fused to tubercle De on head as well as on Abd. V, and body without digitate tubercles of the new species can be easily differentiated from D. quadrilobata, as the latter has 4 digitate tubercles on the last two abdominal segments, and separation of tubercle Di from De on the head as well as on Abd. V.

The new species is similar also to Womersleya vicina ( Denis,1934), from Indochina, in the arrangements of developed body tubercles, the presence of 5 chaetae on tubercle Di+De of head, the presence of an inner tooth on claw and the styliform maxilla. However, it can be separated from the latter one, by the number of mandible teeth (four in the new species vs at least 11 in W. vicina), the presence (in the new species) or absence (in W. vicina) of s chaetae on tubercle Di of the thorax and abdomen, and strong cryptopygy present in the new species and absent in W. vicina.

The new species resembles species of the genus Blasconurella Deharveng & Bedos, 1992, from Thailand, in the following characters: no blue hypodermic pigment, no black ocular pigment, Abd. VI bilobed, body tubercles developed, without tertiary granules and reticulations, eyes 2+2, mouthparts reduced, labral chaetotaxy 0/2, 2, eight tubercles on head, with fusion of An and Fr, Di and De, Dl, L and So, chaeta D migrated to tubercle Cl. However, the new species can be easily separated from the latter by the characters of having additional s-chaetae on terga, fusion tubercle Di and De of Abd. V, an inner tooth on claw, large body size (up to 4.6 mm). Blasconurella species have no additional s-chaetae on tergites, have separated tubercle Di and De on Abd. V, no inner tooth on claw, and a small body size (up to 1.5 mm).

The new species is similar to Thai species, Thaianura umesaoi Yosii, 1961, as both are cryptopygous and have the same arrangement of tubercles on body, but T. umesaoi has Crossodonthina - type mandible.

We temporally place the new species in the genus Rambutanura Deharveng, 1988. The characters of the new species that conform to the diagnosis of Rambutanura are: body large size and convex, without blue pigment. 2+2 unpigmented eyes, labral chaetotaxy as 0/2,2, labium with 11 ordinary chaetae and 2 minute papillae, maxilla styliform. All body tubercles are well developed, the head with 8 tubercles. Plurichaetosis of m chaetae on Ant. IV, plurichaetosis of ordinary and s-chaetae on tergites are present. The new species differs from the diagnosis of the genus Rambutanura in the following characters: mandible with only four teeth, body without finger-like tubercles, body reticulations absent. The new species is very similar to Rambutanura carcharia Smolis, 2007 . Both species have similar shaped mandibles, the same number and arrangement of eyes, large body size ( carcharia up to 7 mm, hunanensis sp. nov. up to 4.6 mm), plurichaetosis of many groups of ordinary chaetae on the body, plurichaetosis of sensilla mou on Ant. IV, same shape of the body macrochaetae and body granules (which are sharp-toothed). The tridentate mandible of Rambutanura carcharia is in contradiction to the diagnosis of the genus. In consideration of these characters (tridentate mandible in R. carcharia and quadridentate mandible in the new species, the absence of finger-like body tubercle, the absence of body reticulations on the new species) we suggest to expand the definition of genus Rambutanura Deharveng, 1988 as follows: body large size and convex, without blue pigment, 2+2 unpigmented eyes, labral chaetotaxy as 0/2,2, labium with 11 ordinary chaetae and 2 minute papillae, mandible tridentate to multi-dentate, maxilla styliform. All body tubercles well-developed, swelling or finger-like in form, reticulations either present or absent, head with 8 tubercles: Cl, Af, 2 Oc, 2 (Di+De), 2 (Dl+L+So), tubercles Di, De and Dl on dorsum of Abd. V fused together on each side of the axis. Antennal s chaetae S1 to S8 subequal, plurichaetosis of mou chaetae on Ant. IV. Plurichaetosis of ordinary and s-chaetae on tergites. Claw with an inner tooth. Morphologically, genus Rambutanura is similar to the genera Womersleya Denis, 1948, Digitanura Deharveng, 1987 and Blasconurella Deharveng & Bedos, 1992.

The new species can be easily distinguished from congeners by its unique characters: quadridentate mandible, an additional s-chaeta present on each tubercle Di from Th. I to Abd. IV, body digitate tubercles absent, and VT with 6 (5) chaetae.

Figures

FIGURE 3. Rambutanura hunanensis Jiang & Dong sp. nov. dorsal tubercles and chaetotaxy.(scale bar 0.5mm)

FIGURES 1–2. Rambutanura hunanensis Jiang & Dong sp. nov. 1, body color in life; 2, habitus.

FIGURES 4–10. Rambutanura hunanensis Jiang & Dong sp. nov. 4, antenna (dorsal side); 5, Ant. III–IV (ventral side); 6, types of dorsal body chaetae (a, Ml. b, Ml. c, Mc. d, Mcc. e–h, me. i, mi. j, s.); 7, mandible; 8, maxilla; 9, tubercles of left side on Abd. III; 10, chaetotaxy of Abd. VI. (scale bar 4, 6, 9, 0.05mm; 5, 7–8, 0.02mm; 10, 0.1mm).

FIGURES 11–14. Rambutanura hunanensis Jiang & Dong sp. nov. 11, dorsal tuberclesof left side on Abd. III; 12, chaetotaxy of Abd.VI; 13,hind leg (lateral-ventralview); 14, ventral chaetotaxyof abdomen.(scale bar 11, 13–15, 0.05 mm; 12, 0.1mm).