Laubieriopsis blakei, Salazar-Vallejo & Zhadan & Rizzo, 2019

Salazar-Vallejo, Sergio I., Zhadan, Anna E. & Rizzo, Alexandra E., 2019, Revision of Fauveliopsidae Hartman, 1971 (Annelida, Sedentaria), Zootaxa 4637 (1), pp. 1-67 : 41-43

Laubieriopsis blakei n. sp.

Figures 24 , 25

urn:lsid:zoobank.org:act:3848A670-DF7C-4F8B-B797-781699985793

Type material. Southeastern Pacific. Chile. Holotype ( LACM 11291 ) and 11 paratypes (2 SEM ECOSUR 210 , LACM 11292 ), SW off Concepcion, R / V Vema, Sta. 17-6 (37°57’ S, 75°08’ W), 4303–4323 m, Menzies trawl, 21 Mar. 1961 (paratypes 6–8 mm long, 0.5–0.6 mm wide, 15 chaetigers; GP paired, between chaetigers 6 and 7; oocytes not seen by transparency).

Additional material. Southeastern Pacific. Peru. Six specimens ( LACM 0000), W off Pacasmayo, R / V Vema, Sta. 15-65 (07°35’ S, 81°24’ W), 5825–5841 m, Menzies trawl, 5 Dec. 1958 (body wall and chaetae frequently bro- ken, one anterior fragment, AE exposed in one specimen; body 6–10 mm long, 0.2–0.8 mm wide, 15–16 chaetigers; anal papillae two, well developed; GP on right side of posterior margin of chaetiger 6, oocytes not seen) . One specimen ( LACM 7491 ), dried out, chaetigers difficult to count, W off Pacasmayo, R / V Vema, Sta. 15-66 (07°30’ S, 81°25’ W), 5857–5858 m, small bottom trawl, green to black mud, 6–7 Dec. 1958 . Two specimens ( LACM 7505 ), W off Huarney, damaged, most chaetae broken, R/ V Vema, Sta. 15-69 (10°13’ S, 80°05’ W), 6326–6330 m, small bottom trawl, green to black mud, 9 Dec. 1958 (1 with 15, the other with 16 chaetigers) . One specimen ( LACM 7508 ), W off Lima, R/ V Vema, Sta. 15-73 (12°02’ S, 79°08’ W), 5522–5529 m, Menzies trawl, 17 Dec. 1958 (slight- ly dehydrated, AE not exposed; body 6 mm long, 0.4 mm wide, 15 chaetigers; anal papillae two, well developed; GP or oocytes not seen) . One specimen ( LACM 7503 ), and five fragments, W off Pacasmayo, R / V Vema, Sta. 15-74 (07°32’ S, 81°26’ W), 5759–5760 m, Menzies trawl, 19 Dec. 1958 (macerated, many chaetae broken; body 7.5 mm long, 0.8 mm wide, 15 chaetigers; anal papillae minute; GP paired, between chaetal lobes of chaetigers 6 and 7; oocytes not seen) . Chile. One specimen ( LACM 7502 ), NW off Valparaiso, R/ V Vema, Sta. 15-85 (32°29’ S, 72°28’ W), 4097–4532 m, Menzies trawl, 1 Jan. 1959 (AE exposed, pharynx not everted; body 6.5 mm long, 0.6 mm wide, 15 chaetigers; anal papillae minute; GP on left side, between chaetal lobes of chaetigers 6 and 7, oocytes not seen) . Eighteen specimens ( LACM 7504 ), W off Concepción, R / V Vema, Sta. 17-3 (36°15’ S, 76°51’ W), 4030–4032 m, standard bottom trawl, 14 Mar. 1961 (4.7–7.5 mm long, 0.4–0.8 mm wide, 15 chaetigers; GP paired, about halfway between chaetal lobes 6 and 7, visible in larger specimens; oocytes in chaetigers 5–8, about 100 µm) . Five specimens ( LACM 7509 ), one incomplete, W off Concepción, R / V Vema, Sta. 17-4 (37°10.0’ S, 77°42.5’ W), 4116 m, standard bottom trawl, 15 Mar. 1961 (6.5–9.0 mm long, 0.5–0.7 mm wide, 15 chaetigers; GP paired, about halfway between chaetal lobes 6 and 7; oocytes in chaetigers 5–8, about 100 µm) . 18 specimens ( LACM 7510 ), one broken, SW off Concepción, R / V Vema, Sta. 17-5 (38°15’ S, 76°00’ W), 3739–3824 m, standard bottom trawl, 16 Mar. 1961 (6.2–9.4 mm long, 0.5–0.8 mm wide, 15 chaetigers; GP paired, about halfway between chaetal lobes 6 and 7; oocytes in chaetigers 5–8, about 100 µm) . One specimen ( LACM 7507 ), WNW off Concepción, R / V Vema, Sta. 15-87 (35°44’ S, 76°22’ W), 4059 m, Campbell grab, 10 Jan. 1959 (AE exposed, pharynx everted; body 7 mm long, 0.8 mm wide, 15 chaetigers; anal papillae minute; GP not seen, oocytes 100 µm) . 18 specimens ( LACM 7491 a), and fragments, SW off Concepción, R / V Vema, Sta. 17-6 (37°57’ S, 75°08’ W), 4303–4323 m, Menzies trawl, 21 Mar. 1961 (2 for SEM; AE exposed and pharynx everted in one specimen; body 6.3–9.0 mm long, 0.6–1.0 mm wide, 15 chaetigers; anal papillae minute; GP paired, between chaetigers 6 and 7, rarely also between 5 and 6; oocytes not seen, perhaps immature; some cross sections in chaetigers 2, 6, and 14 revealed they were mature specimens but the anterior body wall is dark brown and this avoids observing the gonads by transparency) .

Etymology. This species is named for Dr. James A. Blake in recognition of his many publications on polychaetes, several of which deal with deep-sea families. The epithet is a noun in the genitive case.

Diagnosis. Laubieriopsis with 15 chaetigers. Chaetigers 1–3 with two tapered aciculars and two capillaries per ramus. Chaetigers 4–15 with one acicular and one capillary per ramus. GP paired, on chaetigers 6/7.

Description. Holotype (LACM 11291) and paratypes (LACM 11292) complete, some with anterior body region slightly darker than posterior one, others pale ( Fig. 24A ); parapodia biramous, all chaetae brownish, many without tips or broken, rugose. Body subcylindrical, sometimes constricted after chaetiger 3, or swollen medially, holotype 8 mm long, 0.6 mm wide, 15 chaetigers, integument slightly damaged. Chaetigers 1–3 short, progressively longer, 2–3 times wider than long ( Fig. 25A ); following chaetigers as long as wide, posterior segments longer than wide. Pygidum not exposed in most specimens. Integument iridescent, rugose, opaque, inner organs barely visible.

Anterior end not exposed; prostomial and peristomial features unknown. Chaetigers 1–3 with two slightly falcate aciculars and two slightly falcate capillaries per ramus ( Figs 24B , 25B, C ). Interramal papillae globular, tiny, sessile.

Chaetigers 4–15 with a single acicular and a single capillary per ramus ( Fig. 25D ), both progressively longer towards posterior end. Interramal papillae globular, tiny, becoming pedunculate towards posterior end.

Pygidium with anus terminal, as a vertical slit separating it into two cushion-shaped lateral lobes, each with a digitate papilla of variable length ( Figs 24C , 25F ), and sometimes one pair of tiny additional papillae ( Fig. 25G ).

Genital papillae paired, low rounded projections, left one damaged in holotype, sometimes hemispheric, present between chaetal lobes of chaetigers 6 to 7, sometimes with tiny basal, lateral spines ( Figs 24A , inset, 24B, 25A, D, E). Genital papillae rarely unpaired, duplicated in two successive segments or rarely duplicated along the same side in successive segments.

Variation. There were 72 specimens as additional material. Their size was 6–10 mm long, 0.2–1.0 mm wide, with 15 chaetigers (only two specimens with 16 chaetigers). Genital papillae were paired in most specimens, limited to either side of body (7 specimens), usually the right side, or not seen (2 specimens), and in three others genital papillae were visibly duplicated, also in the border between chaetigers 5 and 6.

Remarks. Laubieriopsis blakei n. sp. resembles L. petersenae because both have only 15 chaetigers. However, as indicated in the key above, they differ in the type of anterior aciculars, in the number of anterior thoracic segments, and in the type of genital papillae. In L. blakei n. sp. aciculars are tapered, there are only three thoracic chaetigers, and genital papillae are paired, whereas in L. petersenae aciculars are bidentate, there are four thoracic chaetigers, and genital papillae are single. Another ecological difference is the depth where these species thrive; L. blakei n. sp. is an abyssal species, whereas L. petersenae is a shelf species.

The limited variation in the number of chaetigers is regarded as a growth anomaly because of its low frequency, and likewise the duplication of paired genital papillae in two successive segments.

Distribution. Southeastern Pacific, off Peru to Chile, in sediments at 3739–5858 m depth.

Figures

FIGURE 24. Laubieriopsis blakei n. sp., paratype (ECOSUR 210). A. Dorsal view, asterisk indicates left genital papilla (inset: close-up of left genital papilla, arrow points to spine). B. Anterior region, dorsal view. C. Posterior region, dorsal view. Scale bars: A: 0.5 mm, B, C: 0.2 mm.

FIGURE 25. Laubieriopsis blakei n. sp., paratypes (ECOSUR 210). A. Same as figure 24, anterior region, dorsal view (arrow points to left genital papilla). B. Same, chaetiger 2, left parapodium, notochaetae. C. Another specimen, chaetiger 3, left para- podium, neurochaetae. D. Same as A, chaetigers 6 and 7 (arrows point to genital papillae). E. Same, left genital papilla, seen from above (asterisk indicates spine with broken tip, arrow point to base of broken acicular). F. Same, posterior region, dorsal view. G. Another paratype, posterior region, dorsal view. Scale bars: A: 0.3 mm, B: 18 µm, C: 14 µm, D: 0.1 mm, E: 10 µm, F: 200 µm, G: 170 µm.