Paranura nakamurai Kasai, 2023

Kasai, Hiro & Sawahata, Takuo, 2023, Four new saproxylic species of Paranura Axelson, 1902 (Collembola: Neanuridae Neanurinae) from Japan, Zootaxa 5339 (6), pp. 501-519 : 506-509

Paranura nakamurai Kasai sp. nov.

[Japanese name: Himeshiro-ibonashi-tobimushi]

Figs 12–23 , Tables 3–4

Type material. Holotype: female, Japan, Honsyu, Niigata Prefecture, Sado-shi, Sado Island , Kanaishimbo (alt. 341 m, 38°04'28"N 138°21'07"E), deciduous broadleaf forest, rotten fallen branch, 18-IX-2022, Kahito Nakamura & Hiro Kasai leg. ( NMNS, NSMT-Ap 677) . Paratypes: 3 females ( NMNS, NSMT-Ap 678–680), same data as holotype ; 2 females ( NMNS, NSMT-Ap 681–682), Japan, Honsyu, Niigata Prefecture, Niigata-shi, Mount Kakuda (alt. 163 m, 37°45'46"N 138°49'11"E), deciduous broadleaf forest, rotten fallen branch, 12-XI-2022, Takehiro Ogata & Hiro Kasai leg.

Etymology. This new species is named after Mr. Kahito Nakamura, the collector of the type series.

Diagnosis. 2+2 black eyes on head. Yellowish white body color. Tubercles Cl and Af on the head developed and reticulations present. Ant. II with 11 chaetae. Chaetae O, A, E, and three ocular chaetae present on head. Lateral area on head with 6 chaetae L and 10 chaetae (L+So). Th. II–III with 2 and 3 ordinary chaetae De respectively. Abd. IV with 2 ordinary chaetae Dl. Tubercles Di on Abd. V developed and fused, with 2+2 chaetae Di. Abdomen without clavate chaetae. Furcal remnant with 3–4 mesochaetae and 5–6 microchaetae. Tibiotarsi without chaeta M.

Description. Body length (without antennae) 0.77–1.61 mm in adults. Color of the body yellowish white ( Fig. 12A ). 2+2 black eyes ( Fig. 12B ).

Chaetal morphology. Four types of dorsal ordinary chaetae. Long macrochaetae (Ml) short, weakly thickened, and apically acuminated ( Fig. 22 ); some lateral chaetae longer and strongly acuminated apex. Short macrochaetae (Mc) morphologically similar to Ml, but much shorter. Mesochaetae (me) and microchaetae (mi) similar to ventral chaetae: thin, smooth, and pointed. S–chaetae of tergites thin and smooth.

Antennal morphology and chaetotaxy. Antenna 4-segmented. Ratio of antennal segments I: II: III + IV = 1:1:1.6–1.8. Dorso-central area on Ant. III–IV weakly granulated. S-chaetae of Ant. IV short and thick, S1 and S2 slightly thinner than others ( Fig. 14 ). Apical bulb distinct and trilobed. Chaetotaxy of antennae shown in Table 3b and Figs 14–15 .

Mouthparts. Buccal cone relatively long and rounded at apex. Labrum chaetotaxy 4/2,5,4 ( Fig. 16 ). Labium with 4 basal, 3 distal, and 3 lateral chaetae, papillae x absent ( Fig. 18 ). Mandible with 3 teeth. Maxilla styliform.

Cephalic tubercles and chaetotaxy. Tubercles Cl and Af developed ( Figs 13, 17 ). Tubercle Af divided into two large parts along the midline, reticulations present. Chaetotaxy of the central area complete, all macrochaeta lengths subequal ( Figs 13, 17 ). Lateral area with 6 chaetae Dl and 10 chaetae (L+So). Dorsal chaetotaxy of the head shown in Table 3a and Figs 13, 17 . Group Vi with 6+6 chaetae. Groups Vea, Vem, and Vep with 4, 3, and 3 chaetae respectively.

Body tubercles and chaetotaxy. Tubercles Di on Abd. V developed and fused along the midline ( Figs 13, 19 ), around the tubercle Di weakly raised. On Abd. I–IV, chaetae De far from each other, sensory chaeta halfway between De1 and Dl1 ( Fig. 13 ). Abd. VI with tubercles fused into a single, one ventral chaeta located along the midline ( Fig. 23 ). Dorsal chaetotaxy shown in Table 4 and Fig. 13 . Furcal remnant with 3–4 mesochaetae and 5–6 microchaetae. Genital plate with 5–12 chaetae in females. Ventral chaetotaxy shown in Table 4 and Fig. 21 .

Legs. Trochanter with 5 chaetae. Tibiotarsi I, II, and III with 18, 18, and 17 chaetae respectively, and chaeta M absent. Unguis without inner tooth ( Fig. 20 ). Chaetae B4 and B5 short. Chaetotaxy of the legs shown in Table 4 and Fig. 20 .

Remarks. Paranura nakamurai sp. nov. is most similar to P. bisetosa Deharveng, 1989 , having 2+2 eyes, a head with chaeta O and 3 ocular chaetae, and 2 ordinary chaetae De on Th. II. However, P. nakamurai sp. nov. differs from P. bisetosa in the development of the tubercle Af on the head (in P. bisetosa not developed), tubercles Di on Abd. V fused (in P. bisetosa separate), Abd. IV with 2 ordinary chaetae De (1 in P. bisetosa ), chaeta M on the tibiotarsus absent (in P. bisetosa present), and microchaetae present on the furcal remnant (in P. bisetosa absent). P. nakamurai sp. nov. is also similar to P. kedrovayensis Smolis & Deharveng, 2015 but they clearly differ in the reticulations on head (in P. nakamurai sp. nov. present, in P. kedrovayensis absent), labral formula (4/2,5,4 in P. nakamurai sp. nov. vs. 4/2,4,4 in P. kedrovayensis ), number of ordinary chaetae De on Th. II and III (2 and 3in P. nakamurai sp. nov. vs. 3 and 4 in P. kedrovayensis ), tubercles Di on Abd. V (in P. nakamurai sp. nov. developed, in P. kedrovayensis not developed), and microchaetae on the furcal remnant (in P. nakamurai sp. nov. present, in P. kedrovayensis absent).

Figures

FIGURE 12. Paranura nakamurai sp. nov.: A, live specimens; B, lateral views of specimen in ethanol.

FIGURES 13–23. Paranura nakamurai sp. nov.: 13, habitus and dorsal chaetotaxy; 14, dorsal chaetotaxy of Ant. III–IV; 15, ventral chaetotaxy of Ant. III–IV; 16, labrum; 17, dorsal chaetotaxy and tubercles of central area on head; 18, labium; 19, fused tubercles Di of Abd. V; 20, chaetotaxy of tibiotarsus III and unguis; 21, ventral chaetotaxy of Abd. II–VI; 22, chaeta Di1 of Abd. V; 23, ventral chaetotaxy of Abd. VI.