Namalycastis borealis Glasby, 1999

Conde-Vela, Víctor Manuel, 2013, Namalycastis occulta n. sp. and a new record of N. borealis (Polychaeta: Nereididae: Namanereidinae) from the Northwestern Caribbean Sea, Zootaxa 3721 (5), pp. 475-487 : 482-485

Namalycastis borealis Glasby, 1999

Figure 3 , Table 2

Namalycastis borealis Glasby 1999: 37 –39, Fig. 12 a–g. Vanegas-Espinosa et al. 2007: 120–122, Figs. 1 a–i.

Material examined. ECOSUR P-2651 (8), Isla Tamalcab, Bahía de Chetumal, Quintana Roo, México, 11 May 2012, inland, in litter leaf of red ( Rhizophora mangle ) and white ( Laguncularia racemosa ) mangroves, col. Elda Aurora Canul Ramírez; ECOSUR P-2652 (7), Isla Tamalcab, Bahía de Chetumal, Quintana Roo, México, 18 May 2012, inland, in litter leaf of red ( Rhizophora mangle ) and white ( Laguncularia racemosa ) mangroves, col. EACR.

Description. 15 specimens revised and measured, some incomplete. Body subcylindrical, uniform in width anteriorly, tapering over far posterior region. Dorsal side convex, ventral side flat. Epidermal pigments present dorsally, dark brown, more intense in anterior and posterior end, light brown in rest of body; dorsal surface glossy in reflected light. Specimens without sexual products.

Prostomium hexagonal, wider than long, cleft absent or inconspicuous, with narrow longitudinal groove extending from tip to posterior prostomium. Antennae subconical, extending beyond the palpostyle. Two pairs of eyes, black, oval, trapezoidal arrangement or almost lineal, posterior pair slightly smaller, with crystalline structure evident ( Fig. 3 A).

Peristomium with four pairs of tentacular cirri. Dorsal and ventral cirri with similar length, dorsal tentacular cirri 1.2 times longer than ventral tentacular cirri. Posterodorsal tentacular cirri extending posteriorly to chaetiger 3 or 4. Cirrostyles smooth, without folds, joints or pigment; cirrophores distinct, pigmented. Phranyx smooth, without paragnaths or papillae ( Fig. 3 A). Jaws dark brown, with single robust terminal tooth, 7 teeth along cutting edge ( Fig. 3 F).

Parapodia sub-biramous, notochaeta rarely present throughout body. Dorsal cirri cirriform in anterior and middle parapodia; increasing in length towards posterior parapodia becoming foliose; always longer than ligule. Ventral cirri cirriform, subconical posteriorly, always shorter than dorsal cirri or ligule. Cirrophores conspicuous ( Figs. 3 C–E).

Notochaetae include one sesquigomph spiniger, absent in chaetiger 10, present rarely in some parapodia along the body, without apparent pattern. Notopodial spiniger with blade finely serrated, fine pointed tip. Neurochaetae in type A arrangement, i.e. supra-acicular chaetae include heterogomph falcigers in preacicular fascicles and sesquigomph spinigers in postacicular fascicles; sub-acicular chaetae include heterogomph falcigers in preacicular fascicles and heterogomph spinigers in postacicular fascicles.

Supra-acicular falcigers with 12 teeth, blade moderately serrated with 1/3 of distal margin edentulated, rounded tip ( Fig. 3 G). Supra-acicular spinigers with blade moderately serrated basally, becoming finely distally, tips finely pointed ( Fig 3 J). Sub-acicular falcigers with 4 teeth, blade moderately serrated with 3/4 of distal margin edentulated, rounded tip ( Fig. 3 H). Sub-acicular spinigers with blade blade finely serrated, fine pointed tip ( Fig. 3 I). Aciculae dark brown, paler proximally, tips occasionally protrudes slightly the ligule.

Pygidium with crenulated rim, anus dorsoterminal. Anal cirri cirriform, smooth, arising ventrolaterally, length equal than pygidium width. Prepygidial segment without cirri or chaetae ( Fig. 3 B).

Variation. The specimens of Chetumal Bay had an average length of 22.67 mm (SD ± 10.16) and a maximum width of 2.50 mm, while the average number of chaetigers was 65 (SD ± 21).

The specimens examined vary in the followings features in parapodia: ratio between length of dorsal cirri and length of ligule varies from 1.5–2.0 at chaetiger 10, 1.5–2.2 in middle chaetigers and 1.8–3.0 in posterior chaetigers; ratio between length of ventral cirri and length dorsal cirri varies from 0.2–0.5 at chaetiger 10, 0.2–0.5 in middle chaetigers and 0.1–0.4 in posterior chaetigers. Variation in neurochaetae include: 1–2 heterogomph falcigers and 2–8 sesquigomph spinigers in supra-acicular fascicles; 2–5 heterogomph falcigers and 0–2 heterogomph spinigers in sub-acicular fascicles. Uppermost sub-acicular falcigers often have 6–8 teeth. Additionally, parapodia in mid body tend to have more chaetae than the rest and chaetal blades tend to increase its length posteriorly. The jaws had always seven teeth and similar size and shape, except one in which the most distal tooth is smaller than the rest ( Fig. 3 F). The variation in proportion between length of anal cirri and width of pygidium is 0.7–1.3.

The analysis of correlation ( Table 2 ) shows that body length and other body measurements have a strong relationship; however, the best estimator for body length is L3, followed by W10.

Remarks. This species are closely related with N. abiuma (Müller & Grube in Grube) and practically differ only in the different serrations on chaetae (Glasby 1999). In cladistic analysis N. terrestris Pflugfelder, 1933 are related with this species and differs in the number of supra-neuroacicular falcigers and the relative length of dorsal cirri. N. borealis Glasby is easily recognizable of N. occulta n. sp.: differs mainly in having eyes, present pigments and notochaetae, the new species lacks this features.

The specimens identified are within the range of variation described for N. borealis Glasby, 1999 , however are shorter than the material examined by Glasby. The specimens described for Venezuela (Vanegas-Espinoza et al. 2007) are similar in size to specimens of Chetumal Bay; the synonymy presented in this paper is based only in the literature and the specimens of Venezuela were not examined, but due to both registers have close affinities probably are the same. As in Belize, this species was found together with Namanereis "amboinensis" (Pflugfelder, 1933). With regard to the latter, it is doubtful their taxonomic identity due to its supposed wide distribution, and requires a detailed study for elucidation. This is the first record of this species from Mexico.

Distribution. Caribbean region. The type locality is Beaufort, North Carolina, United States. Synonymies extend the distribution to Bahamas and Bonaire, and other records for Belize, Grand Cayman and Aruba. Most recently records from Lake of Maracaibo, Venezuela (Vanegas-Espinoza et al. 2007), and this paper extends the distribution to Mexican Caribbean coasts.

Figures

FIGURE 1. Namalycastis occulta n. sp. A. Anterior end, dorsal view (insert: close-up of antennae). B. Posterior end, dorsal view. C. Jaw, dorsal view (insert: tip of jaw, frontal view). D. Chaetiger 3, right parapodium, frontal view. E. Chaetiger 36, right parapodium, frontal view. F. Chaetiger 88, right parapodium, frontal view. G. Supra-acicular heterogomph falciger, chaetiger 36. H. Sub-acicular heterogomph falciger, chaetiger 36. I. Sub-acicular heterogomph falciger, chaetiger 3 (insert: distal tip). J. Sub-acicular heterogomph spiniger, chaetiger 36 (insert: blade tip). K. Supra-acicular sesquigomph spiniger, chaetiger 36. A – B, D – K. from holotype ECOSUR P- 0151; C. from paratype ECOSUR P- 0152. Scale bars: A, B, 0.25 mm; C, D, E, F, 0.05 mm; G, H, I, J, K, 0.01 mm.

FIGURE 3. Namalycastis borealis Glasby, 1999. A. Anterior end, dorsal view. B. Posterior end, dorsal view. C. Chaetiger 3, frontal view. D. Chaetiger 32, frontal view. E. Chaetiger 47, frontal view. F. Jaw, dorsal view. G. Supra-acicular heterogomph falciger, chaetiger 47. H. Sub-acicular heterogomph falciger, chaetiger 47. I. Sub-acicular heterogomph spiniger, chaetiger 47. J. Supra-acicular sesquigomph spiniger, chaetiger 47. A, C – J. from specimen ECOSUR P- 0000; B. from specimen ECOSUR P- 0000. Scale bars: A, B, 0.5 mm; C, D, E, F, 0.15 mm; G, H, I, J, 0.01 mm.