Leeonychiurus polychaetosus (Lee & Park, 1986) comb. nov.

(Figs 9–16; Table 2)

Onychiurus polychaetosus Lee & Park, 1986: 13 .

Diagnosis. Formula of pso as 22/233/33343 dorsally, 01/000/01120 ventrally; sensory clubs on Ant. III organ granulated; PAO composed of 30–36 compound vesicles; Th. II–III terga with 5–6+5–6 chaetae along axial line; Th. I, II and III sterna with 0+0, 1+1, 1(4)+1 chaetae between legs respectively; chaeta a1 on upper anal valve present.

Material examined. Holotype female (Collection no. 84-43-3), 19 paratypes (females and males); Korea, Sanhodong-gul cave, Yeoryang-ri, Bug-myeon, Jeongseon-gun, Gangweon-do Province, 22.x.1984 (Insect Collection, Department of Biology Education, Jeonbug National University, Korea).

Redescription. Body length: up to 3.9 mm. Body color white.

Pseudocelli formula: 22/233/33343 dorsally and 01/000/01120 ventrally. Subcoxae 1 of legs I–III with 1 pso each (Figs 9, 10, 11). Psx not seen. Psp formula: 00/011/11110 dorsally and absent ventrally.

Head: Antennae as long as head. Length ratio of antennal segments I: II: III: IV = 1: 1.6: 1.3: 2.4. Ant. I with 15 chaetae. Ant. II with 33–45 chaetae. AIIIO composed of 5 papillae, 5 guard chaetae, 2 small sensory rods and 2 granulated sensory clubs; lateral ms just behind sensory organ. Ant. IV subapical organite with apex globular; invaginated apical bulb absent; basolateral ms at about 1/2 length from base, above the second proximal row of chaetae. (Fig. 12). Antennal base with smaller granulation. PAO composed of 30–36 compound vesicles arranged in 2 rows along axis of organ. Dorsal cephalic chaeta d0 absent. 3+3 p-chaetae between two inner posterior pso on head (p1 absent). 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 formula of chaetae 4/342. Labial papillae of AC type. Labium with 6 proximal, 4 basomedian and 6 basolateral chaetae. Postlabial chaetae 5–7+5–7 along ventral groove.

Body chaetotaxy: Polychaetosis prominent and chaetal arrangement rather irregular and variable (Figs 9, 10). Dorsal chaetae differentiated in meso- and macrochaetae, S-chaeta indistinct. Tiny and blunt ms, present on Th. II and III. Th. I tergum with 13–16+13–16 chaetae. Th. II–III terga each with 5–6+5–6 chaetae and Abd. I–III terga each with 4+4 chaetae on both sides of axial line. Abd. IV tergum with axial chaeta p0, sometimes with asymmetrical chaetae along axial line; Abd. V tergum with two axial chaetae m0 and p0; Abd. VI tergum with 3–4 axial chaetae a0, m0 and p0 (Fig. 1). Th. I, II and III sterna with 0+0, 1+1, 1(4)+1 chaetae respectively. Subcoxae 1 of legs I–III with 14–18, 10 –12 and 8–12 chaetae respectively.

Appendages: Tibiotarsi I, II and III with 21–22 (11, 8, 2–3), 21–22 (11, 8, 2–3) and 21 (11, 8, 2) chaetae respectively. Unguis slender, carinate, with lateral teeth. Unguiculus slender and pointed, 0.5 times as long as inner edge of unguis, with angular inner basal lamella. Ventral tube with 27–37 pairs of distal chaetae, without anterior and basal chaetae. Furca reduced to a finely granulated area, with 4 dental chaetae in one row posterior to furcal rudiment; three manubrial rows of chaetae present (Fig. 13–15).

Anal valves with numerous acuminate chaetae; each lateral valve with chaetae a0, 2a1, 2a2, b0, 2b1 and 2b2; upper valve with chaetae a0, 2a1, 2a2, b0, 2b1, 2b2, c0, 2c1, 2c2 (Fig. 16), other lateral microchaeta generally present symmetrical or asymmetrically. Anal spines set on large papillae, curving, and 0.75 times as long as inner edge of hind unguis.

Ecology. Deep areas of a cave in the mid-east of Korean Peninsula.

Discussion. L. polychaetosus is clearly differentiated from all other species of the genus by the number of dorsal and ventral pseudocelli and polychaetosis (Table 2). The species is unique among the genus by the lack of d0 chaeta on head; this character may be connected with polychaetosis related with large size (ca. 3 mm) and adaptation to cavernicolous life.

*In the original description of O. gulinensis, pso on Th. I tergum (1+1), psx on Abd. III (1+1) and Abd. VI (3) were overlooked.