Lumbrinerides kristiani, Miura, 2017

Miura, Tomoyuki, 2017, Classification and Morphological Variations of the Japanese Species of Lumbrinerides (Annelida: Lumbrineridae), Species Diversity (Auckland, N. Z.) 22 (1), pp. 7-27 : 23-24

Lumbrinerides kristiani sp. nov.

( Figs 13 , 14 )

Material examined. Holotype: NSMT-Pol H-610, Seisui-Maru Cruise 1984-R-07, Station 402 B (intact female), Irago Strait, 34°20.2′N, 136°60.0′E, 39.2 m, 13 September 1984; 3 paratypes: NSMT-Pol P-611 (one female, two immature), same site as holotype; seven paratypes: NSMT-Pol P-611 (one female, six immature), Station 402 A, same site as holotype; three paratypes: NSMT-Pol P-612 (two females, one immature), Station 502 A, Ago Inlet, 60.0 m, 16 September 1984.

Non-type material. ( EK A) Seisui-Maru Cruise 1984-R-07, Stations, 201 A (including two immature); 301 A (one immature, one juvenile) and 301 B (three immature, one juvenile); 302 A (one immature, one juvenile) and 302 B (one immature); 402 A (one juvenile); 403 A (two immature, one juvenile) and 403 B (one juvenile); 501 B (one male); 502 B (two immature); 701 B (one immature). ( KII A) Tansei-Maru Cruise KT-84-12, Station 11-2 (one immature); Station 12-1 (one immature). ( BUNG) Tansei-Maru Cruise KT-84-12, Stations 31 (three immature); 33 (one immature).

Description. The holotype is an intact female measuring 20 mm long by 0.47 mm wide with 175 chaetigers.

Prostomium 1.94 times longer than wide. Peristomium comprising two apodous rings ( Fig. 13A ). First five parapodia reduced ( Fig. 13D, E ). Postchaetal lobes rounded with a very short projection on central outer edges between chaetigers 5–8 ( Fig. 13E, F ). Projection becoming larger, fused with basal parts, being digitiform to conical from chaetiger 9 ( Fig. 13 G–J). Limbate chaetae broadly limbate at least on first several parapodia, becoming narrower posteriorly. Limbate chaetae numbering two per parapodium on chaetigers 1–6, three on chaetigers 7–22, two on chaetigers 23–87 and one on chaetigers 88–126 ( Fig. 14 ). Far posterior parapodia on chaetigers 127–173 lacking limbate chaetae ( Fig. 13J ). A single limbate chaeta on each parapodium on last chaetiger in holotype ( Fig. 14 ). Simple bidentate hooded hooks beginning on chaetiger 1, two per parapodium on chaetigers 1–6, one on chaetigers 7–22, two on chaetigers 23–26, three (sometimes two or four) on chaetigers 27–174 and none on chaetiger 175 in holotype ( Fig. 14 ). Mandibles with four concentric lines on anterior flared end in holotype, but sometimes eight in larger specimens of 0.66 mm width ( Fig. 13C ). Maxillae I with a single well-defined accessory tooth ( Fig. 13B ). Maxillae II with three blunt teeth on both plates. Maxillae III lacks defined teeth. Maxillae IV comprising long oval plates without teeth.

Biological notes. The spawning season of this species is thought to be in summer since a collection in September 1984 ( EK A) included matured specimens with fully developed gametes .

Variations. Accessory teeth on maxillae I usually numbered one (rarely two) on one or both sides. In the case of two accessory teeth on each maxilla I, such were intermeshed with only one being well developed whereas the remaining tooth could be recognized only from their internal cavities found in the medulla of maxillae I. The prostomium length to width proportion varied from 1.3 to 2.6. First simple hooks always occurred at the first parapodium, the number of anterior reduced parapodia varying between four and six. Well developed parapodia with prolonged postchaetal lobes began from chaetigers 7–11 (chiefly 9–10).

Remarks. This species differs from other Japanese species in having a combination of character states, such as having only one accessory tooth on maxillae I in general, a small number of anterior reduced parapodia and simple hooks starting on chaetiger 1. Lumbrinerides dayi differs from the new species in having ten anterior reduced parapodia instead of four to six. One of the specimens identified as L. dayi by Imajima (1985) may in fact be referred to this new species, due to having six anterior reduced parapodia, a single accessory tooth on maxillae I and hooks starting on anterior parapodia (parapodium 4 in an Imajima’s damaged specimen).

Etymology. The new species is named for Dr Kristian Fauchald, Research Zoologist at the Smithsonian Institution, who encouraged me at the beginning of my scientific life and passed away 4 April 2015.

Distribution. Off Hamana Lake (40–41 m), off Tawara (40–61 m), Irago Strait (39–80 m), Ago Bay (39–60 m), off Kumano River (39 m), off Susami, Kii Channel (73–101 m), off Tsukumi, Bungo Channel (72–76 m), on sandy substrates, Pacific coast of Japan; East China Sea (40 m).

Figures

Fig. 13. Lumbrinerides kristiani sp. nov., paratype (NSMT-Pol P-612: A, B), and holotype (NSMT-Pol H-610: C–J). A, lateral view of anterior end; B, dorsal view of maxillae; C, ventral view of mandibles; D, anterior view of parapodium 1; E, anterior view of Parapodium 5; F, anterior view of parapodium 7; G, anterior view of parapodium 10; H, anterior view of parapodium 18; I, anterior view of parapodium 20; J, anterior view of parapodium 152.

Fig. 14. Chaetal distribution pattern in Lumbrinerides kristiani sp. nov., holotype (NSMT-Pol H-610), one of paratypes (NSMT-Pol P-611: BW 0.66mm) and non-type materials. Numbers of hooks (closed circles) and limbate chaetae (open circles) per parapodium plotted on each parapodium from first to last chaetigers of fragmented specimens.