Kainonereis chamberlini, Conde-Vela & Wu & Salazar-Vallejo, 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 : 9-11

Kainonereis chamberlini sp. n.

( Figs. 1 A-C, E; 2C-D; 4A-K)

urn:lsid:zoobank.org:act:1CD1B233-2D85-4ADA-B5C8-030C41AD2E53

Type material: Caribbean Sea, Colombia. Holotype USNM 1422199, female, R/V Pillsbury, Cruise 6806, St. 768 (12°33'N, 71°11'W), NE off La Guajira Peninsula, Colombia, 65 m, 28 July 1968. Northwestern Atlantic Ocean, Bahamas. Paratype UMML 22.1126, female, R/V Pillsbury, Cruise 6406, St. 197 (27°59'N, 79°20'W), NW Little Bahama Bank, 576 m, 11 August 1964.

Type locality: Northeastern off La Guajira Peninsula, Colombia, 65 m depth.

Etymology: Named after the late Dr. Ralph Vary Chamberlin, a very prolific taxonomist in several groups, as an homage to his work in polychaete taxonomy and proposing the genus Kainonereis .

Description: Holotype ( USNM 1422199) complete, female epitoke, delicate, 8 mm long, 0.6 mm wide at chaetiger 10, 56 chaetigers ( Figs. 4 A-C). Paratype ( UMML 22.1126) female epitoke complete, delicate, prostomium and posterior end damaged, anal cirri missing, 9 mm long, 0.5 mm wide at chaetiger 10, 58 chaetigers ( Figs. 4 D- E). Body yellowish, tapering posteriorly, stained with green-methyl to improve contrast, no staining pattern observed.

Prostomium longer than wide, pentagonal, anterior margin entire, medial shallow groove present; one pair of antennae, biarticulated, ceratophore three times longer than ceratostyle; eyes black, anterior eyes reniform, posterior ones ovate, anterior eyes slightly larger than posterior ones ( Figs. 1A ; 4 B-C). Achaetous ring as long as first chaetiger; anterior cirri with distinct cirrophores, cirrostyles articulated, longest one reaching chaetiger 6 ( Figs. 1A ; 4 B-C). Pharynx not everted; jaws enlarged, cutting edge smooth ( Fig. 1A ).

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 with both noto- and neuroaciculae. In chaetigers 5-7 ( Figs. 1 B-C; 4C, H), dorsal discs calyx-like (i.e. with a concave inner surface), cirrostyle narrow, laterally inserted. Notopodial dorsal ligule as long as notopodial ventral one; both ligules digitate, separated by an intermediate rounded process. Acicular neuropodial ligule subconical, twice longer than postchaetal lobe; neuropodial ventral ligule digitate, slightly longer than acicular neuropodial lobe. Ventral cirrus cirriform, half as long as acicular neuropodial lobe.

In chaetigers 8-14 ( Figs. 2C ; 4I ), dorsal cirrus cirriform, shorter than notopodial dorsal ligule. Notopodial dorsal ligule half as long as notopodial ventral one; both ligules subconical, tapering, and separated from each other; prechaetal lobe inconspicuous. Acicular neuropodial ligule subconical; postchaetal lobe digitate, half as long as acicular neuropodial ligule; neuropodial ligule subconical, slightly shorter than acicular neuropodial lobe. Ventral cirrus cirriform, shorter than neuropodial ventral ligule.

Parapodia from 15 to end of body similarly modified throughout ( Figs. 1E ; 2D ; 4 J-K). Dorsal cirrus smooth, slender, as long as notopodial dorsal ligule, becoming slightly longer than towards posterior chaetigers, with two small basal lamellae, upper lamella slightly larger than lower one; dorsal lamella twice longer than upper one, distinction between it and upper lamella always conspicuous. Both notopodial dorsal and ventral ligules digitate to lanceolate, subequal; both notopodial ligules separated by a rounded process. Acicular neuropodial ligule digitate; postchaetal lobe becoming into a lamella, as wide as acicular neuropodial ligule, distal end bilobate; neuropodial ventral ligule digitate, medially inserted to acicular neuropodial ligule, slightly longer than it. Ventral cirrus cirriform, as long as acicular neuropodial ligule, with two small basal lamellae.

Notochaetae homogomph spinigers. 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. Neuropodial heterogomph spinigers pectinate, teeth fine, decreasing towards tip ( Fig. 4F ); heterogomph falcigers pectinate, teeth fine, distal tooth stout ( Fig. 4G ), supra- and sub-acicular falcigers similar. Pygidium not modified, with two lobes; anal cirri faintly articulated, as long as last 3 segments.

Remarks: The study of material collected during the University of Miami Deep Sea Expeditions allowed us to find two specimens of this species and encouraged us to revise the genus. The specimens were found in two places and at different depths, with a distance of about 2000 km between them. Though the paratype is anteriorly damaged and diagnostic features such as antennae and anterior cirri are missing, parapodial features are almost identical to those present in the holotype.

The species can be recognized easily by its cup-like discs, shorter than remaining structures in the same parapodium. Paratype has discs compressed (laterally flattened), so the central hollow is inconspicuous, likely as consequence of the fixation process, but their size, shape and position are very similar to those present in the holotype. Other distinctive features are that dorsal cirri are shorter than notopodial dorsal ligules, and notopodial ventral ligules are as long as acicular neuropodial ligules in chaetigers 8-14; whilst in remaining species, dorsal cirri are subequal to longer than notopodial dorsal ligules, and notopodial ventral ligules are longer than acicular neuropodial ligules. The jaws of K. chamberlini sp. n were observed through the partly transparent body wall, having an almost smooth cutting edge, presumably as a consequence of epitoky ( Fig. 1A ). Natatory parapodia of K. chamberlini sp. n. resemble those found in K. alata , mainly in the clear differentiation between upper dorsal cirri and dorsal lamellae, and proportion of ligules and lamellae, but the two species can be separated by both the shape and proportion of elytriform structures, and shape of ligules along chaetigers 8-14.

Figures

Fig. 1. Morphology of Kainonereis Chamberlin, 1919 species. K. chamberlini sp. n. A-C, E (USNM 1422199); K. polaris comb. n. D (USNM 55514). (A) anterior end, dorsal view (transparency, 10x); (B) elytriform dorsal cirrus from mounted parapodium 6, anterior view; (C) same, non-mounted, lateral view; (D) parapodium 3, anterior view; (E) parapodium 40, anterior view. Abbreviations: Ac, anterior cirri; An, antennae; Cr, cirrostyle; DoLa, dorsal lamella of dorsal cirri; Di, disc; Jw, jaws; LDc, lower lamella of dorsal cirrus; LVc, lower lamella of ventral cirrus; NaL, neuroacicular ligule; NeV, neuropodial ventral ligule; NoD, notopodial dorsal ligule; NoV, notopodial ventral ligule; Ph, pharynx; PoL, neuropodial postchaetal lobe; Pr, prostomium; PreL, notopodial prechaetal lobe; St, stalk; UDc, upper lamella of dorsal cirrus; UVc, upper lamella of ventral cirrus; Vc, ventral cirrus; VeLa, ventral neuropodial lamella. Scale bars: A = 0.3 mm; B-E = 50 µm. All chaetae omitted.

Fig. 4. Kainonereis chamberlini sp. n., A-C, F-H, J, K, holotype (USNM 1422199); D, E, I, paratype (UMML 22.1126). (A) whole specimen, dorsal view; (B) anterior end, dorsal view; (C) same, lateral view; (D) whole specimen, dorsal view; (E) same, lateral view; (F) neuropodial sub-acicular heterogomph spiniger, chaetiger 6; (G) neuropodial sub-acicular heterogomph falciger, parapodium 6; (H) parapodium 6, anterior view; (I) parapodium 11, anterior view; (J) parapodium 25, anterior view; (K) parapodium 40, anterior view. Scale bars: A, D = 1 mm; B, C, E = 0.5 mm; F, G = 10 µm; H-K = 0.1 mm.

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.