Paranura tsushimaensis 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 : 502-504

Paranura tsushimaensis Kasai sp. nov.

[Japanese name: Rurihoso-ibonashi-tobimushi]

Figs 1–11 , Tables 1–2

Type material. Holotype: male, Japan, Kyushu, Nagasaki Prefecture, Tsushima-shi, Tsushima Island , Kamitsushimacho (alt. 33 m, 34°35'52"N 129°25'10"E), evergreen forest, rotten fallen branch, 27-XI-2022, Kahito Nakamura & Hiro Kasai leg. ( NMNS, NSMT-Ap 671) . Paratypes: 2 females ( NMNS, NSMT-Ap 672–673) , 2 males ( NMNS, NSMT-Ap 674–675), and juvenile ( NMNS, NSMT-Ap 676); same data as the holotype .

Etymology. The new species is named after the type locality, Tsushima Island.

Diagnosis. 3+3 black eyes on head. Dark blue body color. Body elongated and flattened. Some tubercles present on dorsal side of body, underlined by reticulations. Abd. V four times as long as Abd. VI. Ant. II with 12 chaetae. Chaetae O, A, E, and three ocular chaetae present on head. Lateral area on head with 6 chaetae Dl and 10 chaetae (L+So). Th. II–III with 3 and 4 ordinary chaetae De respectively. Tubercles Di on Abd. V not developed, with 2+2 chaetae Di. Abd. V with 9 ordinary chaetae De+Dl+L. Furcal remnant with 5–7 mesochaetae and no microchaetae. Tibiotarsi with chaeta M.

Description. Body length (without antennae) 1.58–1.83 mm in adults. Color of the body dark blue ( Fig. 1 ). 3+3 black eyes, two anterior and one posterior. Body elongated and flattened ( Fig. 4 ).

Chaetal morphology. Five types of dorsal ordinary chaetae. Long macrochaetae (Ml) relatively long, thickened, sheathed, apically acuminated; some lateral chaetae longer and strongly acuminate at the apex ( Fig. 10 ). Short macrochaetae (Mc) morphologically similar to Ml, but much shorter. Very short macrochaetae (Mcc) relatively thick and weakly acuminated ( Fig. 9 ). 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 = 1:1:1.5. Dorso-central area on Ant. III–IV weakly granulated. S-chaetae of Ant. IV relatively long and thick, S1 and S2 slightly thinner than others ( Fig. 2 ). Apical bulb distinct and trilobed. Chaetotaxy of antennae shown in Table 1b and Figs 2–3 .

Mouthparts. Buccal cone relatively long and rounded at apex. Labrum chaetotaxy 0/2,2 ( Fig. 5 ). Labium with 4 basal, 3 distal, and 4 lateral chaetae, papillae x absent ( Fig. 6 ). Mandible with 3 teeth. Maxilla styliform.

Cephalic tubercles and chaetotaxy. Tubercle Cl weakly developed ( Fig. 4 ). Chaetotaxy of the central area complete ( Fig. 4 ). Lateral area with 6 chaetae Dl and 10 chaetae (L+So). Dorsal chaetotaxy of the head shown in Table 1a and Fig. 4 . Group Vi with 6+6 chaetae. Groups Vea, Vem, and Vep with 4, 3, and 4 chaetae respectively.

Body tubercles and chaetotaxy. Tubercle Dl on Abd. IV, tubercle De+Dl+L on Abd. V, and a unique tubercle on Abd. Vl developed and reticulated ( Figs 4, 11 ). Tubercles Di on Abd. V not developed, with 2+2 chaetae Di. Abd. V very long, four times as long as the last segment of the body ( Figs 4, 11 ). Dorsal chaetotaxy shown in Table 2 and Figs 4, 11 . Furcal remnant with 5–7 mesochaetae and no microchaetae. Genital plate with 28–30 and 12–30 chaetae in females and males respectively. An with 2 mi, rarely one side absent. Ventral chaetotaxy shown in Table 2 and Fig. 7 .

Legs. Tibiotarsi I, II, and III with 19, 19, and 18 chaetae respectively, chaeta M present. Unguis without inner tooth ( Fig. 8 ). Chaetae B4 and B5 long. Chaetotaxy of the legs shown in Table 2 and Fig. 8 .

Remarks. Paranura tsushimaensis sp. nov. is the third species with a bluish body color, a very long abdominal segment V, and reticulations in the dorsal area. P. tsushimaensis sp. nov. is the most similar to P. reticulata Smolis & Deharveng, 2015 , having a head with 3 ocular chaetae, the lateral area of the head with 16 chaetae, and 4 ordinary chaetae De on Th. III. However, this new species is clearly distinguishable from P. reticulata by the absence of prelabral chaetae (in P. reticulata 4), 2+2 ordinary chaetae Di on Abd. V (in P. reticulata 3+3), 9 ordinary chaetae De+Dl+L on Abd. V (in P. reticulata 6–7), and microchaetae absent on the furcal remnant (in P. reticulata present). This new species is also similar to P. s-uenoi Yosii, 1955 . However, the new species differs with 3 ocular chaetae on the head (in P. s-uenoi 2), 2 ordinary chaetae De on Th. I (in P. s-uenoi 3), and 4 ordinary chaetae De on Th. III (in P. s-uenoi 3).

Figures

FIGURE 1. Live specimen of Paranura tsushimaensis sp. nov.

FIGURES 2–11. Paranura tsushimaensis sp. nov.: 2, dorsal chaetotaxy of Ant. III–IV; 3, ventral chaetotaxy of Ant. III–IV; 4, habitus and dorsal chaetotaxy (holotype); 5, labrum; 6, labium; 7, ventral chaetotaxy of Abd. II–VI; 8, chaetotaxy of tibiotarsus III and unguis; 9, chaeta Di1 of Abd. V; 10, long macrochaeta on Abd. IV; 11, dorsal chaetotaxy and tubercles of Abd. V–VI. ✕—missing chaetae.