Semiodera caribea

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 9-12

Semiodera caribea (Grube & Ørsted in Grube, 1859) new spelling

Figure 1

Siphonostomum cariboum Grube & Ørsted in Grube 1859:4–5; Grube 1877:67, 71; Salazar-Vallejo & Eibye-Jacobsen 2012:1394 (non Ehlers 1887:158–161, Pl. 42, Figs 6–9, Pl. 43, Fig. 1, nec Hartman 1956:294–295).

Type material. Caribbean Sea. Holotype of Siphonostomum cariboum (ZMUC-331), off St. Croix (17º44'23" N, 64º44'20" W), 11 m, 18 Sep. 1845, A.S. Ørsted, coll.

Additional material. Gulf of Mexico, Florida. One specimen ( USNM 55985 ), RV Columbus Iselin, Transect 6, Stat. 2640 (29°34'29.3" N, 87°54'30.3" W), 35 m, Jul. 1976 (dorsal shield removed, body wall macerated; 16 mm long, 1.5 mm wide, cephalic cage 11 mm long, 65 chaetigers) . Yucatán Peninsula, México . Campeche. Seven specimens ( ECOSUR 1729 ), two complete, Champotón (19º21'20" N, 90º43'24" W), coralline rock, 2 m depth, 16 Feb. 1999, J.R. Bastida & SISV, coll. (complete 13.0– 18.5 mm long, 1.3–2.0 mm wide, cephalic cage 6 mm long, 57–72 chaetigers; no gonopodial slits in chaetiger 5) . Two specimens ( ECOSUR 1730 ), one complete ,

damaged, El Hueso, Champotón, 2 m depth, 5 May 2005, L.F. Carrera & SISV, coll. (complete 15 mm long, 2 mm wide, cephalic cage 5 mm long, 62 chaetigers; gonopodial slits in chaetiger 5). Yucatán. One specimen ( ECOSUR 1732 ), anterior fragment, Río Lagartos , coralline rock, 3 m depth, 18 Feb. 1999, J.R. Bastida & SISV, coll. Four specimens ( ECOSUR 1731 ), two complete, Ría Lagartos (21°37'16.7" N, 88°10'32.6" W), coralline rock, 3 m, 30 May 2005, L.F. Carrera, coll. (complete 10–19 mm long, 1.5–2.0 mm wide, cephalic cage 4.5–6.0 mm long, 60–68 chaetigers; gonopodial slits in chaetiger 5). Quintana Roo. One specimen ( ECOSUR 1734 ), complete, DIF Aventuras (20°21'47" N, 87°19'53" W), 21 Mar. 1992, SISV & Eunice Salazar, coll. (16 mm long, 1.5 mm wide, cephalic cage 6.5 mm long, 85 chaetigers; no gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1735 ), breaking into two pieces, DIF Aventuras (20°21'47" N, 87°19'53" W), 23 Mar. 1992, L.F. Carrera & SISV, coll. (13 mm long, 2 mm wide, cephalic cage 6 mm long, 65 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1736 ), complete, Buenavista, Xahuayxol (18°30'42" N, 87°45'30" W), 27 Sep. 1996, SISV & L.F. Carrera-Parra, coll. (14 mm long, 1.5 mm wide, cephalic cage 5 mm long, 68 chaetigers; gonopodial slits in chaetiger 5; some oocytes between cephalic cage chaetae, each about 200 µm). Thirteen specimens ( ECOSUR 1737 ), five complete, Punta Nizuc (21°01'23" N, 86°46'52" W), coralline rock, 3 m depth, 1 Sep. 1997, SISV et al. coll. (complete 21–22 mm long, 1.8–2.0 mm wide, cephalic cage 7 mm long, 65–78 chaetigers; gonopodial slits in chaetiger 5). Five specimens ( ECOSUR 1738 ), four complete, Punta Herradura (18°32'26" N, 87°44'30" W), coralline rock, 3 m depth, 28 Oct. 1997, L.F. Carrera & SISV, coll. (6–12 mm long, 1 mm wide, cephalic cage 4–5 mm long, 44–60 chaetigers; largest specimen with gonopodial slits in chaetiger 5). Two specimens ( ECOSUR 1739 ), one complete, Buenavista, Xahuayxol (18°30'42" N, 87°45'30" W), coralline rock, 3 m depth, 4 Jun. 1998, L.F. Carrera & SISV, coll. (complete 17 mm long, 2 mm wide, cephalic cage 6.5 mm long, 46 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1740 ), complete, mature female, DIF-Aventuras (20°21'47" N, 87°19'53" W), coralline rock, 1.5 m depth, 28 Feb. 1999, J.R. Bastida & SISV, coll. (16.5 mm long, 2 mm wide, cephalic cage 6.5 mm long, 66 chaetigers; gonopodial slits in chaetiger 5; oocytes 200 µm in diameter). One specimen ( ECOSUR 1741 ), complete, Majagual (18°43'01" N, 87°42'23" W), coralline rock, 1.5 m depth, 22 Mar. 2000, L.F. Carrera & SISV, coll. (13 mm long, 1.5 mm wide, cephalic cage 6 mm long, 61 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1742 ), mature female, breaking into two pieces, Majagual (18°43'01" N, 87°42'23" W), coralline rock, 1.5 m depth, 22 Mar. 2000, L.F. Carrera & SISV, coll. (14 mm long, 2 mm wide, cephalic cage 5 mm long, 76 chaetigers; gonopodial slits in chaetiger 5; oocytes 150–200 µm in diameter). Two specimens ( ECOSUR 1743 ), complete, Punta Nizuc (21°01'23" N, 86°46'52" W), coralline rock, 2 m depth, 8 Feb. 2001, J. R. Bastida, coll. (10–15 mm long, 1–2 mm wide, cephalic cage 4.0– 7.5 mm long, 49–59 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1744 ), complete, Henequén, Contoy Island (21°29'20" N, 86°47'44" W), 1 Mar. 2001, J.R. Bastida, coll. (9 mm long, 1 mm wide, cephalic cage 4.5 mm long, 58 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1745 ), complete, Boca Laguna Puerto Viejo, Contoy Island (21°29'20" N, 86°47'44" W), 1 Mar. 2001, J.R. Bastida, coll. (6.5 mm long, 1 mm wide, cephalic cage 4 mm long, 52 chaetigers; gonopodial slits in chaetiger 5 not seen). Four specimens ( ECOSUR 1746 ), two complete, an anterior fragment of a mature female, coralline rock, 2 m depth, Río Indio , 17 Mar. 2001, L.F. Carrera, coll. (complete 12–14 mm long, 1.5–2.0 mm wide, cephalic cage 5.5–7.0 mm long, 60–44 (regenerating the posterior region); gonopodial slits in chaetiger 5; oocytes 150–200 µm in diameter). One specimen ( ECOSUR 1747 ), without posterior end, some chaetae broken, Sedena Beach, Cozumel(20º25' N, 86º 55' W), 24 Mar. 2001, SISV, coll. (16 mm long, 1.5 mm wide, cephalic cage 5 mm long, 32 chaetigers; gonopodial slits in chaetiger 5). Nine specimens ( ECOSUR 1748 ), seven complete, Xcacelito, coralline rock, 1 m depth, 26 Oct. 2002, L.F. Carrera, coll. (complete 12–17 mm long, 1–2 mm wide, cephalic cage 5.0– 6.5 mm long, 63–66 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1749 ), complete, in calcareous tube, Punta Sur, Contoy Island (21°27'34.86" N, 86°47'07.98" W), 0.5 m, coralline rocks, 2 Mar. 2005, J.R. Bastida, coll. (9 mm long, 1.5 mm wide, cephalic cage 4 mm long, 40 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1750 ), Ixlaché, Contoy Island, Q. Roo, México, 2 m, boring in coral rock, 25 Feb. 2008 (complete, 10.5 mm long, 1.3 mm wide, cephalic cage 2 mm long, 58 chaetigers, gonopodial slits in chaetiger 5) .

Description. Holotype (ZMUC-331) dark gray, integument scaly ( Fig. 1A), apparently dried-out formerly, previously dissected, now almost broken about the widest part, fracture continued posteriorly ( Fig. 1C), and distal region separated. Body cylindrical, posteriorly tapering; 12 mm long (in three pieces), 1.5 mm wide, cephalic cage 3.5 mm long, 47 chaetigers (37+10). Tunic thin, integument regularly corrugated (looking scaly), free from sediment cover; body papillae short rounded, two rows per chaetiger, body in cross-section oval.

Anterior end observed in additional specimens. Cephalic hood exposed, short. Prostomium low cone, four black eyes, anterior ones fused, posterior ones not coalescent ( Fig. 1G). Caruncle poorly developed. Palps pale, longer than longest branchiae; palp keels rounded, low. Lips fused, not separable in lateral, dorsal or ventral, ventral pharyngeal organ exposed.

Branchiae cirriform, sessile on branchial plate, arranged in a single, curved row, about 10 filaments, decreasing in size ventrally, largest about half as long as palps. Nephridial lobes pale, double, visible above the eyes, placed about the internal margin of larger, lateral branchiae.

Cephalic cage chaetae as long as 1/3 body length, or slightly longer than twice body width. Chaetigers 1–2 involved in the cephalic cage, others with broken chaetae. Cephalic cage chaetae arranged in short rows, notopodial lateral, neuropodial ventral. Chaetiger 1 with 8 noto- and 6 neurochaetae, chaetiger 2 with 6 noto- and six neurochaetae per bundle.

Anterior dorsal margin of first chaetiger with a low projection, with two long papillae. Anterior chaetigers without especially long papillae. Chaetigers 1–3 increasing in size posteriorly. Sand cemented anterior shield over chaetigers 1–5, posterior margin fading ( Fig. 1B). Chaetal transition from cephalic cage to body chaetae gradual; first falcate neurohooks from chaetiger 7 ( Fig. 1B, insert). Gonopodial slits not seen in holotype (other specimens with short, low, dark, ventral papillated lobes in chaetiger 5).

Parapodial development obscured by dehydration; parapodia poorly developed, lateral; neuropodia short low lobes, ventrolateral. Notopodia with a single, inferior digitate papilla, slightly longer than surrounding ones. Neuropodia without longer papillae. Noto- and neuropodia very close to each other.

Median notochaetae arranged in transverse tufts, collapsed; most notochaetae broken, blackish, about ¼–1/5 body width, about 2 per fascicle. Neurochaetae multiarticulate capillaries in chaetigers 1–3 ( Fig. 1D); chaetigers 4–6 with 1–2 pseudocompound hooks ( Fig. 1E). Falcate neurohooks from chaetiger 7, arranged in transverse rows, 2 per fascicle in chaetigers 7–12, 3 throughout the rest of the body, final caudal chaetigers with only one neurohook per fascicle.

Posterior region tapering to a blunt cone, pygidium a muscular ring, without cirri.

Variation. There is some variation on the pigmentation of the anterior end. Many specimens are dark-grayish or even blackish along the first 3–10 chaetigers, being darkest on anteriormost chaetigers, whereas others are less pigmented. In fact, the pigmentation is concentrated in the external body wall and is independent of sexual maturity. Since the anterior end is exposed during feeding or during fecal pellets removal, this pigmentation may be a response to exposure to light, but no such field observations or details exist about the relative position in the bored calcareous rocks. Further, the specimens collected in more turbid waters, along the Gulf of Mexico shores, are paler with almost no trace of pigmentation, and this would reinforce the hypothesis that pigmentation depends on light levels.

Unless the specimens are turgid or swollen, the tunic will look areolate, and this makes identification easier, even with a single fragment, because other similar species have a smooth tunic even if the body segments are contracted (see Remarks below).

The holotype shows only two large, falcate neurohooks in median chaetigers. Other specimens have two additional ones per ramus, often smaller and less curved; these were probably broken in the holotype. In a better preserved specimen, there are two neurohooks in chaetigers having transitional neurohooks and up to chaetiger 6, then 3–5 in chaetigers 7–14(20 in larger specimens), becoming reduced to 3–4 in a few chaetigers and then 1–2 per ramus in far posterior chaetigers.

Remarks. Semiodera caribea (Grube & Ørsted in Grube, 1859), new combination, differs from S. inflata ( Treadwell, 1914) n. comb., which has been erroneously recorded in the Grand Caribbean region, by having two irregular rows of dorsal papillae instead of a single one.

There are three other species with a dorsal shield restricted to the dorsal surface and with 2–3 transverse series of papillae: S. dubia ( Treadwell, 1929) n. comb., S. blakei n. sp. and S. tovarae n. sp. However, S. caribea is unique by having a scaly integument instead of a smooth one.

The original name should be changed to caribea , which is the correct noun in the genitive case. This epithet has been widely employed in different taxa. The holotype of S. caribea has been dried out but most of the external morphology can be recognised. The dorsal shield is not extended beyond notopodial bases; the integument has not lost the scaly appearance due to the presence of abundant rounded low papillae. This feature is not related to the preservation fluid since other specimens collected in the same locality and preserved in 95% ethanol, do not become scaly.

Distribution. Grand Caribbean Sea, from the Northwestern region ( Isla Contoy) to the US Virgin Islands

(Lesser Antilles), boring calcareous substrates in shallow water.