Lobella lucifera sp. nov.

[Japanese name: Akahoshi-aka-ibotobimushi]

Figs 1D, 1I, 6–8; Tables 6–9

Material examined. Holotype: male, collected at Nishinakasone, Hirara, Miyako Island, Okinawa, Ryukyu Archipelago, Japan (24.8104°N, 125.3135°E, elevation 33 m) on 10 May 2023 by Ohira, A., Nakamori, T. and Takaesu, R. Deposited in the National Museum of Nature and Science, Tsukuba, Japan (NSMT-Ap 709; INSD accession number LC857139 for COI gene).

Paratypes: 3 males, 3 females and 1 unknown, collected at Nishinakasone, Hirara, Miyako Island, Okinawa, Ryukyu Archipelago, Japan (24.8104°N, 125.3135°E, elevation 33 m) on 10 May 2023 by Ohira, A., Nakamori, T. and Takaesu, R. Deposited in the National Museum of Nature and Science, Tsukuba, Japan (NSMT-Ap 710–716; INSD accession numbers LC857138 and LC857140 for COI gene) .

Other materials examined. One male, two females, collected at Nishinakasone, Hirara, Miyako Island, Okinawa, Ryukyu Archipelago, Japan (24.8104°N, 125.3135°E, elevation 33 m) on 10 May 2023 by Ohira, A., Nakamori, T. and Takaesu, R .

Diagnosis. Eyes 3+3, black. Apically displaced sgd, close to i on Ant. IV. Mandible tridentate with the apical tooth subdivided into 3 toothlets. Maxilla styliform. Labrum chaetal formula 2/2, 2. Labium with 10 chaetae and 2 x. Cephalic O chaeta present, head Oc with 3 chaetae, De with 2 chaetae. De of Abd. II and III with 4 chaetae. Th. I–Abd. VI lacking unpaired tubercles. Sensory chaeta present on tubercle L of Abd. IV. Di of Abd. V with 3 chaetae, including 1 microchaeta. Tubercle De separated from tubercle Dl on Abd. V. Tubercle Di of Th. II and III with 3 chaetae each. Unguis with 1 inner tooth.

Description. Body length approximately 2.5–3.1 mm. Colour bright red in living specimen (Fig. 1D) and white in alcohol. Eyes 3+3, black (Fig. 6B). Postantennal organ absent. Antennae shorter than head. Ant. III and IV dorsally fused (Fig. 7A). Ant. I and II with 7 and 11 chaetae, respectively. Ant. III organ with 5 sensory chaetae, including sgd, sgv, ms and 2 finger-like rods in separate pits. Apically displaced sgd, close to i, Ant. IV with trilobed apical bulb, dorsal chaetotaxy with 8 S and i (Fig. 7A). Mandible thin and tridentate with the apical tooth subdivided into 3 toothlets (Fig. 7D). Maxilla head consisting of 2 stylets: one with 2–3 minute apical teeth (Fig. 7E). Labrum granulated, chaetal formula 0/2, 2 (Fig. 7B). Labium with 10 chaetae and 2 x (Fig. 7C).

Cephalic tubercles and chaetotaxy. Cephalic area with 14 separate tubercles. Chaetotaxy of dorsal head as in Fig. 6B. Tubercle Cl with 4 chaetae, An with 4 chaetae, Fr with 3 chaetae (O chaeta present), Oc with 3 chaetae, Di with 2 chaeta, De with 2 chaetae, Dl with 4 chaetae, L+So with 11–15 chaetae (Fig. 6B, Table 6). Ventral chaetotaxy of the head as in Fig. 6A and Table 7.

Body tubercles and chaetotaxy. Th. I–Abd. VI lacking unpaired tubercles. Th. I with 3+3 tubercles (Di, De, Dl). Th. II–Abd. IV with 4+4 tubercles, respectively (Di, De, Dl, L). Abd. V dorsally with 3+3 tubercles (Di, De, Dl). Abd. VI with 1+1 tubercles. Body chaetotaxy as in Fig. 6B and Table 8. Sensory chaetae on the body acuminate, long and smooth; macrochaetae rough, sheathed and apically rounded (Fig. 8). Formula of s on half terga of Th. II–Abd. V as 2+ms, 2/1, 1, 1, 2, 1. Sensilla present on tubercles De on Th. II to Abd. V and tubercles Dl on Th. II to III. Lateral sensilla present on tubercle L on Abd. IV. Ventral chaetotaxy of Abd II –VI as in Fig. 6C.

Appendages. Chaetotaxy of legs, ventral tube and furcular remnant as in Table 9. Tibiotarsi I–III with 19, 19 and 18 chaetae, respectively. Unguis with 1 inner tooth. Unguiculus absent (Fig. 7F). Ventral tube with 4+4 chaetae. Furcula absent. Furcular remnant with 3–4 chaetae (Fig. 6C). Genital plate with 32–42 chaetae (male: 32–42; female: 32–42). Each ventral anal valve with 15 Ve chaetae and 2–3 hr macrochaetae (Fig. 6C). Dorsal anal valve with 3 hr microchaetae (Fig. 6C).

Etymology. The name lucifera, as a Latin adjective, is derived from another Latin adjective lucifer (bringing light), referring to the light-emitting ability of the species.

Ecology. This species was found in leaf litter and on dead wood. The species emitted light when stimulated (Fig. 1I). Lobella lucifera sp. nov. can be fed plasmodia of F. septica in the laboratory.

DNA barcoding. The p -distances for the COI gene within L. lucifera sp. nov. (4 individuals) were 0.0%. No COI gene sequences with>85% identity to the new species were found in the GenBank or BOLD databases. The p -distances of the COI gene between L. lucifera sp. nov. and other congeneric species, i.e., Lobella monstrum Ohira & Nakamori, 2023 (LC760502 – LC760504; Ohira et al. 2023), L. sauteri (LC760492 – LC760494; Ohira et al. 2023) and L. yambaru (LC760495 – LC760497; Ohira et al. 2023), collected from their respective type localities, were 18.6%, 16.8% and 14.8%, respectively.

Remarks. Lobella lucifera sp. nov. is most similar to L. sauteri and L. yambaru according to the key of Lobella described by Ohira et al. (2023). However, the new species can be distinguished from them by having 1 of the 3 chaetae on Di tubercles of Abd. V as a microchaeta (2 of the 3 chaetae as microchaetae in L. sauteri and L. yambaru), and blunt macro- and mesochaetae (pointed in L. sauteri and L. yambaru).