Lumbrinerides tamaii, 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 : 24-25

Lumbrinerides tamaii sp. nov.

( Figs 15–17 )

Lumbrineriopsis sp.: Tamai et al. 1989: appendix table 2.

Material examined. Holotype: NSMT-Pol H-613 (immature) and 14 paratypes: NSMT-Pol P-614 (14 immature) Tenryu River mouth, 34°38.1′N 137°47.6′E, 5–10 m, 5 May 1983. 19 paratypes: NSMT-Pol P-615 (four males, 15 immature), Tosa Bay, 15 m, 26 November 1980; four paratypes: NSMT-Pol P-616 (one female, three immature), same site, 23 December 1980; 20 paratypes: NSMT-Pol P-617 (20 immature), same site, 8 June 1981.

Non-type material. (Tenryu) 14 juveniles, same site and date as holotype; (Tosa N) five juveniles; (Tosa D) one juvenile; (Tosa J) 10 juveniles.

Description. The holotype comprises an anterior body fragment (0.76 mm wide) with 71 chaetigers. One of paratypes NSMT-Pol P-615 from Tosa Bay is an incomplete male (ca. 50 mm long, 0.64 mm wide) with 188 chaetigers with some caudal chaetigers missing. Another paratype NSMT- Pol P-616 from Tosa Bay in December 1980 is an intact female with a discoidal pygidium ( Fig. 15B ).

Prostomium length about 1.2 times width in holotype, 1.1–2.7 in paratypes ( Figs 2 , 15A ). Peristomium comprising two apodous rings. First 11 parapodia reduced. Parapodia fully developed posteriorly on chaetiger 12 in holotype and on chaetigers 11–13 in paratypes ( Fig. 15G, H ). First 11 parapodia with two broadly limbate chaetae in holotype, thereafter three per parapodium becoming two on chaetigers 32–71. Relatively undamaged and smaller paratypes with a single limbate chaeta on each parapodium on posterior chaetigers, eventually being lost ( Fig. 16 ). Holotype with simple bidentate hooded hooks on chaetiger 1 ( Figs 16 , 17 ), two per parapodium on first 11 chaetigers, one on chaetigers 12–21, two or three on subsequent chaetigers. Mandibles with five concentric lines in holotype, five to eight in adult paratypes ( Fig. 15D ). Maxillae I with three weakly projected accessory teeth with pulp cavities in holotype, two or three in paratypes ( Fig. 15C ). Maxillae II with three blunt intermeshing teeth on both plates.

Biological notes. Specimens from Tosa Bay, reported as Lumbrineriopsis sp. by Tamai et al. (1989), included specimens with sperm or eggs in the coelom during November and December in 1980 when water temperatures fell to below 20°C ( Tamai et al. 1989: 73, fig. 13). The spawning season of this species is thus thought to be in winter.

Variations. The number of accessory teeth on Maxillae I varied between two and three in the Tosa Bay population, the maxillae occasionally having asymmetrical forceps ( Fig. 15C ). In such a case, the left side tends to have three teeth and the right two. Tosa Bay specimens with two accessory teeth on one side of Maxillae I were dominant (56%), but those with three teeth on both sides were dominant (79%) in the Tenryu River mouth population ( Fig. 2 ). Well-developed parapodia with prolonged postchaetal lobes started from chaetigers 11–13 in adults, but from chaetiger 8 in a small juvenile (0.3 mm wide).

Remarks. This species is unique among its congeners in having three accessory teeth on at least one side of Maxillae I. It also spawns in Winter, unlike, for example, L. shimodaensis , L. hayashii , and L. kristiani spawning in Summer.

Etymology. The new species is named for Dr K. Tamai who kindly donated specimens collected from Tosa Bay.

Distribution. Tenryu River mouth (10 m); Tosa Bay (15 m), sandy substrate, Pacific coast of Japan.

Figures

Fig. 15. Lumbrinerides tamaii sp. nov., paratype (NSMT-Pol P-616, female: A, B, H) and paratype (NSMT-Pol P-615: C–G). A, anterior end, lateral view; B, posterior end, dorsal view; C, maxillae, dorsal view; D, mandibles, ventral view; E, parapodium 1, anterior view; F, parapodium 10, anterior view; G, parapodium 20, anterior view; H, parapodium 19, anterior view.

Fig. 16. Chaetal distribution pattern in Lumbrinerides tamaii sp. nov. collected from off Tenryu River mouth, holotype (NSMT- Pol H-613), and paratypes (NSMT-Pol P-614). Numbers of hooks (closed circles) and limbate chaetae (open circles) per parapodium plotted on each parapodium from first to last chaetigers of fragmented specimens.

Fig. 17. Chaetal distribution pattern in Lumbrinerides tamaii sp. nov. collected from Tosa Bay, paratypes (NSMT-Pol P-615). Numbers of hooks (closed circles) and limbate chaetae (open circles) per parapodium plotted on each parapodium from first to last chaetigers of fragmented specimens.

Fig. 2. Frequency histograms (%) for each local sample containing more than 20 specimens (treated initially as operational taxonomic units). Characters assessed included mean number of accessory teeth on maxilla I plates, number of anterior reduced parapodia, prostomium length to width proportion, chaetiger number on which first hooks present, number of concentric lines on mandibles and body width (mm). White bars represent juveniles or growing phase; black bars represent specimens grown sufficiently for use for taxonomic purposes.