Kainonereis elytrocirra ( Wu and Sun, 1979 ), 2018

Conde-Vela, Víctor Manuel, Wu, Xuwen & Salazar-Vallejo, Sergio Ignacio, 2018, Elisesione imajimai Jimi & amp; Eibye-Jacobsen & amp; Salazar-Vallejo 2018, sp. nov., Zoological Studies (Zool. Stud.) 57 (6), pp. 1-24 : 11-13

Kainonereis elytrocirra ( Wu and Sun, 1979)

reinst., comb. n.

( Figs. 2 E-F; 5A-K)

Rullierinereis elytrocirra Wu and Sun 1979:108-111 , Figs. 8 A-P; Wu et al. 1985:61-63, Fig. 32.

Kainonereis alata Sun and Yang 2004:72-73 , Fig. 34 (non Chamberlin, 1919).

Type material: Yellow Sea , China. Holotype MBMCAS A-42 and paratype MBMCAS A- 44 male, R/ V Handan, Collection No. H 130B-5, St. 3073 (34°30'N, 121°30'E), SW Yellow Sea, China, 20 m, 28 April 1959.

Type locality: Southwestern Yellow Sea, China, 20-25 m depth.

Description: Holotype ( MBMCAS A-42) male epitoke complete, 13 mm long, 1 mm wide at chaetiger 10, 59 chaetigers, pharynx everted, anal cirri missing. Paratype ( MBMCAS A-44) male epitoke complete, delicate, anal cirri missing, 12.5 mm long, 1 mm wide at chaetiger 10, 55 chaetigers ( Figs. 5 A-B), presence of sperm in coelom. One of the paratypes ( MBMCAS A-43) missing. Body yellowish, tapering posteriorly, no distinct pigmentation pattern observed.

Prostomium slightly wider than long, pentagonal, anterior margin entire, medial shallow groove present; one pair of antennae, not articulated, tips eroded; eyes black, ovate, anterior eyes slightly larger than posterior ones ( Fig. 5A ). Achaetous ring as long as first chaetiger; anterior cirri with distinct cirrophores, cirrostyles faintly articulated, tips eroded, longest one reaching chaetigers 4-5 ( Figs. 5 A-B). Pharynx smooth; jaws dentate, cutting edge with six teeth visible.

Body divided into two regions: 1) pre-natatory regions include chaetigers 1-14, sub-divided into three regions; 2) natatory region from chaetiger 15 to end of body.

First two chaetigers with neuroaciculae only, remaining chaetigers with noto- and neuroaciculae. In chaetigers 3-4 ( Fig. 5G ), cirrophore of dorsal cirrus swollen basally, ovate, tips narrow, digitate, distinctly separated from bases. Notopodial dorsal ligule as long as notopodial ventral one, notopodial dorsal ligule absent in chaetiger 3; both ligules tapering and separated by a short, rounded prechaetal lobe. Acicular neuropodial ligule subconical, postchaetal lobe longer and narrower than acicular neuropodial ligule; neuropodial ventral ligule tapering, swollen basally and medially, distinctly larger than notopodial ligules. Ventral cirrus pyriform, longer than notopodial and neuropodial lobes.

In chaetigers 5-7 ( Figs. 5 H-I), dorsal discs elytriform, cirrostyle short, indistinctly separated. Notopodial dorsal ligule as long as notopodial ventral one; both ligules tapering and separated by a short, rounded prechaetal lobe. Acicular neuropodial ligule subconical, half as long as postchaetal lobe; neuropodial ventral ligule tapering, slightly longer than acicular neuropodial lobe. Ventral cirrus cirriform, subequal to neuropodial ventral ligule.

In chaetigers 8-14 ( Fig. 2E ), dorsal and ventral cirri slender, cirriform; dorsal cirrus slightly longer than notopodial dorsal ligule, ventral cirrus shorter than neuropodial ventral ligule. Notopodial and neuropodial lobes resembling to those present in chaetigers 5-7.

Parapodia from 15 to end of body modified ( Figs. 2F ; 5 J-K). Dorsal cirrus smooth, slender, as long as notopodial dorsal ligule, with two small lateral, basal lamellae, and one large, dorsal lamella. Both notopodial dorsal and ventral ligules digitate to tapering, subequal; both notopodial ligules separated by a large, rounded prechaetal lobe. Acicular neuropodial ligule enlarged, subconical; postchaetal lobe becoming into a lamella, shorter and as wide as acicular neuropodial ligule, tip bilobate; neuropodial ventral ligule digitate to tapering, medially inserted to acicular neuropodial ligule, as long as it. Ventral cirrus cirriform, as long as acicular neuropodial ligule, with two basal, lateral lamellae.

Notochaetae homogomph spinigers; homogomph falcigers in chaetigers 3-7. Neurochaetae homogomph spinigers and heterogomph falcigers in supra-acicular fascicles; heterogomph spinigers and falcigers in sub-acicular fascicles.

Notopodial homogomph spinigers pectinate, teeth decreasing in size towards tip. Notopodial homogomph falcigers with blunt tips, teeth minute ( Fig. 5C ).

Neuropodial heterogomph spinigers pectinate, large teeth, decreasing towards tip ( Fig. 5F ); heterogomph falcigers pectinate, teeth coarse, distal tooth stout ( Figs. 5 D-E), supra- and sub-acicular falcigers similar.

Pygidium not modified, with two lobes; anal cirri missing.

Remarks: Wu and Sun (1979) made a study about Nicon Kinberg, 1865 and Rullierinereis Pettibone, 1971 species from China, including the proposal for a new genus, Sinonereis . In the key to genera, the unique feature used to distinguish Nicon and Sinonereis from Rullierinereis was the presence of notopodial falcigers in the latter, so it is not surprising they placed their new species in Rullierinereis because they had these chaetae. As a consequence, the diagnosis of Rullierinereis was extended to include species with elytriform dorsal cirri in anterior chaetigers, and one or two notopodial ligules in posterior chaetigers. Later, Wu et al. (1985) made an improved description of R. elytrocirra and detailed that the described largest specimen (the holotype) was a female based on the absence of papillae (p. 63), but they did not explain which papillae they referred to. These papillae presumably are those found commonly in dorsal cirri of natatory parapodia of males, as they described for Leonnates descipiens Fauvel, 1919 : “basalia of dorsal and ventral cirri of transformed parapodia inflated, dorsal cirri with 9-10 papillae” ( Wu et al. 1985:71). However, males of K. alata and K. peltifera sp. n. do not develop such papillae, so such feature is not adequate to distinguish between sexes in this genus. Because the holotype and paratype of K. elytrocirra comb. n. have other sex-related features as presence of notopodial homogomph falcigers in chaetigers 3-7 and the appearing of notopodial dorsal ligules since chaetiger 4, as well as the presence of sperm in the body, these type specimens were regarded as males.

Sun and Yang (2004) noted the resemblance between the modified dorsal cirri in R. elytrocirra and K. alata , and consequently synonymized them. However, we disagree with these authors on this synonymy. The males of the latter species have basally fused antennae, articulate anterior cirri, palps are directed ventrally, notopodial ligules are as long as acicular neuropodial ones in chaetigers 5-7, and notopodial homogomph falcigers with long teeth (half as long as blade width); whilst in males of K. elytrocirra comb. n., antennae are separated, palps are directed forwards, notopodial ligules are twice longer than acicular neuropodial ones in chaetigers 5-7, and notopodial homogomph falcigers have minute teeth; K. elytrocirra comb. n. resembles K. chamberlini sp. n. and K. peltifera sp. n., but the former can be recognized by the shape of notopodial dorsal ligules and large neuropodial postchaetal lobes at chaetiger 10, and also by the shape of discs in chaetigers 5-7.

Figures

Fig. 2. Drawings from parapodia of Kainonereis species. K. alata A, B (USNM 19386); K. chamberlini sp. n. C (UMML 22.1126), D (USNM 1422199); K. elytrocirra comb. n. E, F (MBMCAS A-44); K. peltifera sp. n. G, H (LACM-AHF 7400p); K. polaris comb. n. I, J (USNM 55514). (A) parapodium 11, anterior view; (B) parapodium 40, anterior view; (C) parapodium 11, anterior view; (D) parapodium 25, anterior view; (E) parapodium 12, anterior view; (F) parapodium 20, anterior view; (G) parapodium10, anterior view; (H) parapodium 22, anterior view; (I) parapodium 13, posterior view; (J) parapodium 30, posterior view. Scale bars: A, B = 50 µm; C-H = 0.1 mm; I-J = 0.2 mm. E redrawn from Wu and Sun (1979:109). All chaetae omitted.

Fig. 8. Kainonereis polaris (Hartman, 1967) comb. n. Paratype atoke (USNM 55515). (A) anterior end, dorsal view; (B) close-up of prostomium; (C) anterior end, pharynx, ventral view; (D) tube; (E) notopodial homogomph spiniger, parapodium 13 (insert: closeup of teeth); (F) neuropodial sub-acicular heterogomph falciger, parapodium 13; (G) neuropodial sub-acicular heterogomph spiniger, parapodium 1; (H) parapodium 1, anterior view; (I) parapodium 3, anterior view; J parapodium 13, anterior view; K parapodium 37, anterior view. Scale bars: A-D = 0.5 mm; E = 20 µm; F, G = 10 µm; H-K = 0.2 mm.

Fig. 5. Kainonereis elytrocirra (Wu and Sun, 1979) comb. n. Paratype male (MBMCAS A-44). (A) anterior end, dorsal view; (B) whole specimen, dorsal view; (C) notopodial homogomph falciger, parapodium 4; (D) neuropodial supra-acicular heterogomph falciger, parapodium 4; (E) neuropodial sub-acicular heterogomph falciger, parapodium 7; (F) neuropodial supra-acicular heterogomph spiniger, parapodium 4; (G) parapodium 4, anterior view; (H) parapodium 6, anterior view; (I) parapodium 7, anterior view; (J) parapodium 19, anterior view; (K) parapodium 44, anterior view. Scale bars: A, B = 1 mm; C-F = 10 µm; G-K = 0.1 mm.