Fauveliopsis antri, Jimi & Fujimoto & Ogawa & Fujita & Shigenobu & Imura, 2020

Jimi, Naoto, Fujimoto, Shinta, Ogawa, Akito, Fujita, Yoshihisa, Shigenobu, Yuya & Imura, Satoshi, 2020, Two new species of Fauveliopsidae (Annelida, Sedentaria) from submarine caves and deep sea, Japan, Zootaxa 4878 (2), pp. 385-391 : 387-388

Fauveliopsis antri sp. nov. Jimi

(New Japanese name: doukutsu-yadokari-imomushi-gokai)

( Figure 2 )

Type material. Holotype (NSMT-Pol H-822): 1.2 mm long, 0.2 mm wide; 5 paratypes (NSMT-Pol P-823): 1.0– 1.2 mm long (n=5), 0.2 mm wide (n=5), 32 chaetigers (n=5); all specimens were extracted from small molluscan shells by using forceps, silt sediment, Daidokutsu cave , off Ie Island , Okinawa, Japan, at a depth of 26 m; collected by NJ and SF. 15 additional paratypes (NSMT-Pol P-824): 1.0– 1.5 mm long (n=15), 0.2 mm wide (n=15), 32 chaetigers (n=15); obtained from small molluscan shells by washing with fresh water, silt sediment, Shodokutsu cave (“unnamed cave”), at a depth of 18 m (near to Daidokutsu cave).

Description. Holotype (NSMT-Pol H-822) body complete, 1.2 mm long, 0.2 mm wide, 32 chaetigers, anterior and median parts cylindrical, posteriorly swollen, divided into three different regions by body colour and chaetal features, borderline of median and posterior regions indistinct. ( Fig. 2A ). Body colour whitish in anterior and medial parts, posteriorly transparent, without pigmentation, posterior gut yellowish ( Fig. 2A ). Prostomium partially exposed, fused to peristomium, with a wide, densely ciliated transverse band ( Fig. 2B, C ). Nuchal organ present on dorsal side of peristomium. Mouth opening ventral, T-shaped opening. Integument opaque, rugose, papillated on dorsal and ventral surface. Body papillae 2–3 μm in length ( Figs. 2F , 4A ), digitate, sparsely present on dorsal and ventral sides. Posterior region transparent, rugose; last chaetiger with a transverse band of large, rounded papillae ( Fig. 2F ). Genital papillae not seen.

Parapodia lateral, inconspicuous in all body regions, orange colour in life. Internal papilla pedunculate, on middle of parapodia, along anterior region; smaller and closer to notopodia in median and posterior regions.

Chaetigers 1–3 with chaetae directed anteriorly ( Fig. 2C ): notopodia with straight, thick capillary chaetae (upper) and curved acicular (lower) chaetae; neuropodia with two types: acicular, stout sigmoid acicular (upper) and short sigmoid acicular chaetae. Chaetigers 4 and following with chaetae directed laterally or posteriorly: notopodia and neuropodia with long curved acicular and long capillary chaetae ( Fig. 2D ). All chaetigers with two notochaetae and two neurochaetae ( Fig. 2E ).

Pygidium without anal cirri; anus terminal with some blunt, globular or digitate papillae surrounding anus ( Fig. 2F ).

Etymology. Latin “ antrum ” means “cave” in English. The name is derived from the habitat of this new species. The specific name is a noun in the genitive case.

Distribution. Only known from submarine caves, off Ie Island, Okinawa, Japan, at a depth of 18– 26 m.

Remarks. Fauveliopsis antri sp. nov. can be distinguished from the other members of the genus by the following features: i) 32 chaetigers, ii) chaetigers 1–3 with stout hooks, iii) minute body (about 1 mm in length), iv) all parapodia with same number of chaetae (2 notochaetae; 2 neurochaetae), and v) presence of dorsal and ventral papillae. The most similar species is F. jameoaquensis Núñez in Núñez, Ocaña & Brito, 1997 , also described from caves, by having two chaetae per rami along its minute body. However, the main difference is that F. antri sp. nov., has curved acicular chaetae in chaetigers 1–3, while F. jameoaquensis has straight acicular chaetae ( Núñez et al. 1997). The species also resembles F. brevipodus Hartman, 1971 and Fauveliopsis sp. A Wolf, 1984 by having two chaetae per rami along its body, body with more than 15 chaetigers, and papillae on pygidium. The new species differs from F. brevipodus in the chaetiger number and papillae of pygidium: the new species has 32 chaetigers and multi-papillated pygidium, whereas F. brevipodus has 27–29 chaetigers and smooth pygidium. Fauveliopsis sp. A also has multi-papillated pygidium but the new species has minute body (about 3.0 mm long in Fauveliopsis sp. A) with 32 chaetigers (18–30 chaetigers in Fauveliopsis sp. A). Some specimens of Fauveliopsis levensteinae SalazarVallejo, 2019 also have 32 chaetigers but have many chaetae on posterior chaetigers.

The new species can be distinguished from two other species recorded from Japan, F. glabra and F. challengeriae ( Levenstein 1970; Imajima 2009), by having a minute body and same number of chaetae in all parapodia. Fauveliopsis glabra and F. challengeriae have large bodies (about 5 mm in body length) and the number of chaetae varies depending on the body area.

Figures

FIGURE 2. Fauveliopsis antri sp. nov. (A) holotype (NSMT-Pol H-822). (B–F) paratype (NSMT-Pol P-823). A, fresh specimen, lateral view; B, fixed specimen, prostomium partially exposed, frontal view; C, fixed specimen, anterior end, dorsolateral view; D, fixed specimen, chaetae of chaetigers 1–3; E, chaetae of median chaetigers; F, pygidium. Scale bars = 250 μm (A); 100 μm (B); 100 μm (C); 20 μm (D); 100 μm (E); 20 μm (F). Abbreviation: ca, curved acicular chaetae; cc, capillary chaetae; no, nuchal organ; noc, notochaetae; nuc, neurochaetae; pe, peristomium; pr, prostomium; sa, sigmoid acicular chaetae. White arrows indicate internal papillae. A white arrow head indicates a body papilla.

FIGURE 4. Papillae of the new species. (A) body papilla of Fauveliopsis antri sp. nov. (B) genital papilla of Laubieriopsis soyoae sp. nov. Scale bars = 5 μm (A); 125 μm (B).