Protaphorura minima, Sun, Xin, Zhang, Bing & Wu, Donghui, 2013

Sun, Xin, Zhang, Bing & Wu, Donghui, 2013, Two new species and one new country record of Protaphorura Absolon, 1901 (Collembola: Onychiuridae) from northeast China, Zootaxa 3673 (2), pp. 207-220 : 217

Protaphorura minima sp. nov.

Figs 35–46

Type material. Holotype female, 16 paratype females and 6 paratype males on slides, China: Heilongjiang: Tongjiang: Honghe (47°35’ N, 133°31’ E), 27 Aug. 2010, litter and soil, Wu Donghui et al. leg.

Description. Body color white in alcohol. Size 1.0–1.35 mm in females, 0.9–1.0 mm in males; holotype 1.0 mm. Body slender and elongated.

Pseudocellar formula dorsally: 33/012/33332, absent ventrally ( Figs 35 & 37 ); subcoxa 1 of legs without pso. Parapseudocellar formula ventrally: 00/000/100000; subcoxa 1 of legs without psx. Pseudopores formula dorsally: 00/011/ 111100, ventrally: 00/111/00xx00 ( Figs 35, 37 & 40 ).

Head. Antennae nearly as long as head. Ant. IV with a subapical organite and basolateral ms about 1/3 of segment length from base. Ant. III sensory organ composed of 5 papillae, 5 guard chaetae, 2 small sensory rods, 2 granulated sensory clubs and a lateral ms. Ant. I with 11 chaetae. Ant. II with 17 chaetae. Antennal bases with distinct granulation. PAO composed of 21–26 simple vesicles ( Fig. 36 ). 4+4 p-chaetae between posterior a-pso on head ( Fig. 35 ). Mandible with strong molar plate and 4 apical teeth. Maxilla bearing 3 teeth and 6 lamellae. Maxillary palp simple with 1 basal chaeta and 2 sublobal hairs. Labral chaetae formula 4/342. Labium with 6 proximal, 4 basomedian (E, F, G and f) and 6 basolateral chaetae (a, b, c, d, e, e’) ( Fig. 37 ); labial type A, papillae A–E respectively with 1, 4, 0, 3, 3 guard chaetae. Postlabial chaetae 5(4)+5 along ventral groove ( Fig. 37 ).

Body chaetotaxy. Dorsal chaetotaxy usually with some asymmetry, well differentiated into macro-, meso- and microchaetae. Chaetae s well differentiated dorsally, formula 11/011/222120; weakly marked ventrally ( Figs 35 & 37 ). Th. II–III terga with microsensilla laterally. Th. I tergum with 7–9 chaetae (chaetotaxy type -2- or -1-) ( Figs 35, 38 & 39 ). Abd. I–III and V terga without s’ ( Figs 35 & 43 ). Abd. IV tergum without axial chaeta, Abd. V tergum with p0 axial chaeta, Abd. VI tergum with m0 axial chaeta ( Fig. 35 ). Ratio M/sp on Abd. V 3.0–3.2 ( Fig. 44 ). Straight lines passing through bases of chaetae a1 and m1 parallel on Abd. VI tergum ( Fig. 35 ). Anal spines set on distinct papillae, 0.4 times as long as inner edge of unguis.

Th. I–III sterna with 1+1, 1+1, 1+1 chaetae, respectively. Ventral tube with 8–9+8–9 distal chaetae and 1+1 basal chaetae, without anterior chaetae. Furca reduced to cuticular pocket with 2+2 dental chaetae––1+1 chaetae located on a cuticular fold, remaining 1+1 chaetae located distinctly below fold; three manubrial rows of chaetae present posteriorly to dental chaetae ( Fig. 40 ). Female genital plate with 14–20 chaetae ( Fig. 41 ), male genital plate with 30–34 chaetae ( Fig. 42 ). Male ventral organ present on Abd. VI sternum, bearing two brush-shaped chaetae on each anal valve ( Fig. 45 ). Anal valves with numerous acuminate chaetae; each lateral valve with a0, 2a1 and a2; upper valve with chaetae a0, 2a1, 2b1, 2b2, c0, 2c1, 2c2 ( Fig. 46 ).

Appendages. Subcoxa 1 of legs I–III with 4, 4 and 4 chaetae, subcoxa 2 with 1, 4 and 4 chaetae, respectively. Tibiotarsi of legs I–III with 22 (11, 8, 3), 21 (11, 8, 2) and 23 (11, 8, 4) chaetae, respectively. Unguis with small inner denticle. Unguiculus slender and pointed, 1.2 times as long as inner edge of unguis, without inner basal lamella.

Etymology. The name of the new species refers to its small body size.

Ecology. Found under a pine tree in the Sanjiang Experimental Station of Wetland Ecology, Chinese Academy of Sciences.

Remarks. The new species is particular in having the male ventral organ on Abd. VI sternum (two brushshaped chaetae on each anal valve). Among other species of the genus Protaphorura , P. ajudagi , P. christiani Pomorski, Leithner & Bruckner, 2003 , P. januarii (Weiner, 1977) , P. kopetdagi Pomorski, 1994 , P. s t i r i a c a (Stach, 1946) and P. stogovi Pomorski, 1993 also have the male ventral organ, but they can be easily separated by the combined characters in Table 1 .

The new species resembles P. bicampata in having three pso on dorsal head posteriorly, three pso on Abd. IV tergum, two pso on Abd. V tergum and in lacking pso on subcoxa 1 of legs, but it differs P. bicampata in having 1+1 pso on Th. II tergum (2+ 2 in P. bicampata ), 23–26 vesicles on PAO (29–40 in P. bicampata ), 6 proximal chaetae on labium (7 in P. bicampata ), s-chaetae well differentiated dorsally (weakly marked in in P. bicampata ), 8–9 chaetae on Th. I tergum (13–14 in P. bicampata ), the ratio M/sp on Abd. V 3.0–3.2 (1.4–1.6 in P. bicampata ), the straight lines passing through the bases of chaetae a1 and m1 parallel on Abd. VI tergum (convergent in P. bicampata ), male ventral organ present on Abd. VI sternum (absent in P. bicampata ), psx absent on Abd. II–IV sterna (present in P. bicampata ), s’ absent on Abd. I–III and V (present in P. bicampata ), and in lacking the axial chaeta on Abd. IV tergum (present in P. bicampata ).

Figures

FIGURES 35 – 42. Protaphorura minima sp. nov. 35, dorsal chaetotaxy; 36, PAO; 37, ventral side of head; 38 – 39, Th. I tergum; 40, chaetotaxy of Abd. IV sternum; 41, female genital plate; 42, male genital plate. Scales: 0.1 mm (35, 37, 40), 0.01 mm (36, 38 – 39, 41 – 42).

FIGURES 43 – 46. Protaphorura minima sp. nov. 43, posterior chaetae row of Abd. I tergum; 44, central part of Abd. V tergum; 45, anal valves (male); 46, anal valves (female). Scales: 0.01 mm.