Semiodera dubia ( Treadwell, 1929 ) Salazar-Vallejo, 2012

Salazar-Vallejo, Sergio I., 2012, 3562, Zootaxa 3562, pp. 1-62 : 18-20

Semiodera dubia ( Treadwell, 1929) n. comb.

Figure 5

Stylarioides dubius Treadwell, 1929:9–10 , Figs 25–27.

Pherusa dubia: Hartman 1956:295 .

Pherusa inflata: Hartman 1951:98 ; Milligan 1984:47.11–13, Figs 47.7–8; Rodríguez-Gómez 1988:417, Pl. 12, Figs D–G (non Treadwell, 1914).

Pherusa parmata: Rullier & Amoureux 1979:182 (partim, non Grube, 1878).

Type material. Gulf of Mexico. Three syntypes of Stylarioides dubius ( AMNH-1990 ), Dry Tortugas (24°39'52" N, 82°51'20" W) , Florida, Jun. 1929 (dorsal shield removed; one without posterior end, complete one 30 mm long, 1.5 mm wide, cephalic cage 5 mm long, 45 chaetigers; anterior fragment previously dissected, damaged, 7 mm long, 1.5 mm wide, cephalic cage 4 mm long, 24 chaetigers, tail 9 mm long, 0.7 mm wide, 37 chaetigers; other syntype features used for description below) .

Additional material: Gulf of Mexico. One specimen ( LACM-AHF-2526 ) , Lemon Bay, Florida (26º56'11" N, 82º20'38" W), trawled near pass, from shell aggregate, 25 Jan. 1938 (specimen is partly dehydrated; most chaetae broken; 12 mm long, cephalic cage 7 mm long, 2 mm wide, 60 chaetigers. Dorsal shield on chaetigers 1–4, with a posterior rounded projection). Four small specimens (USNM-129698), SOFLA, Stat. 52 (25°17'48" N, 81°39'48" W), 14 m, 10 Dec. 1982 . Yucatán Península , México . Campeche. Two specimens ( ECOSUR 1728 ) , complete, Campamento Tortuguero, Punta Chen (19°10'53" N, 90°54'10" W), calcareous rock, 1.5 m depth, 24 May 2005, L. Carrera & SISV, coll. (10.0– 16.5 mm long, 1.0– 1.5 mm wide, cephalic cage 4 mm long, 53–54 chaetigers; gonopodial slits in chaetiger 5) . Quintana Roo. Three specimens ( ECOSUR 1723 ) , complete, DIF-Aventuras (20°21'47" N, 87°19'53" W), coralline rock, 1.5 m depth, 21 Mar. 1992, Eunice Salazar & SISV, coll. (11–21 mm long, 1–2 mm wide, cephalic cage 5.0– 7.5 mm long, 52–73 chaetigers; gonopodial slits present in chaetiger 5). One specimen ( ECOSUR 1724 ) , splendid, DIF-Aventuras (20°21'47" N, 87°19'53" W), coralline rock, 1.5 m depth, 22 Mar. 1992, Eunice Salazar & SISV, coll. (20 mm long, 2 mm wide, cephalic cage 6 mm long, 58 chaetigers; gonopodial slits present in chaetiger 5). One specimen ( ECOSUR 1725 ) , cephalic cage with some broken chaetae, Chankanaab (20°26'34" N, 86°59'43" W), coralline rock, 3 m depth, 2 Apr. 1992, SISV, coll. (19 mm long, 1.5 mm wide, cephalic cage 4.5 mm long, 59 chaetigers; gonopodial slits in chaetiger 5). One specimen ( ECOSUR 1726 ) , anterior fragment, Xcacel (20°20'20" N, 87°30'43" W), coralline rock, 1.5 m depth, 5 Jun. 1995, SISV, coll. Six specimens ( ECOSUR 1722 ) , three complete, Buenavista, Xahuayxol (18°30'42" N, 87°45'30" W), coralline rock, 2 m depth, 27 Sep. 1996, L. Carrera & SISV, coll. (complete 14.5–15.0 mm long, 1 mm wide, cephalic cage 5–6 mm long, 57–58 chaetigers; gonopodial slits in chaetiger 5). Four specimens ( ECOSUR 1717 ) , two complete, damaged, Punta Nizuc (21°01'23" N, 86°46'52" W), coralline rock, 2 m depth, 31 Oct. 1997, L. Carrera & SISV, coll. (complete 13–19 mm long, 1.5 mm wide, cephalic cage 6 mm long, 66–71 chaetigers; gonopodial slits present in chaetiger 5; mature female with oocytes 150–200 µm in diameter). Ten specimens ( ECOSUR 1719 ) , two complete, Punta Nizuc , coralline rock, 2 m depth, 1 Sep. 1997, L. Carrera & SISV, coll. (complete 13–17 mm long, 1–2 mm wide, cephalic cage 5–6 mm long, 60–65 chaetigers; gonopodial slits present in chaetiger 5). Five specimens ( ECOSUR) , one complete, Punta Nizuc (21°01'23" N, 86°46'52" W), coralline rock, 4 m depth, 1 Sep. 1997, L. Carrera & SISV, coll. (complete 13.5 mm long, 1.5 mm wide, cephalic cage 4.5 mm long, 62 chaetigers; gonopodial slits present in chaetiger 5). One specimen ( ECOSUR) , complete, slightly damaged, Isla Contoy, Camping, 1 m depth, in Ircinia sponge, 10 Jun. 1999, L. Carrera & SISV, coll. (21 mm long, 2 mm wide, cephalic cage 6.5 mm long, 63 chaetigers; gonopodial slits present in chaetiger 5). Caribbean Sea. Panama. One specimen ( LACM-AHF-2523 ) , broken in two parts, Bocas del Toro Archipelago , Bahia Almirante, Isla Bastimentos, east side, Cayo Coral (9.229° N, 82.142° W), coral rubble, SCUBA, 3 Aug. 2003, J. Norenburg, M. Schwartz, L. Harris, coll. (15 mm long, 1 mm wide, cephalic cage 3 mm long, 58 chaetigers). One specimen ( LACM-AHF- 2524 ) , Bocas del Toro Archipelago, Laguna de Chiriqui, Isla Aqua (9.178° N, 82.054° W), northwest side, from chunks of Teredo-bored wood, among coral rubble and silty sand, 20–25 ft, SCUBA, 8 Aug. 2003, W. Keel & L. Harris, coll. (anterior end exposed, 18 mm long, 2 mm wide, cephalic cage 6 mm long, 60 chaetigers). One specimen and one anterior fragment ( LACM-AHF-2525 ) , Bocas del Toro Archipelago , Bahía Almirante, Cayo Swan (9°27.2’ N, 82°17.9’ W), Stat. 28, coral rubble, 12Aug. 2003, K. Fitzhugh & L.H. Harris, coll. Three specimens ( USNM 66049 ) , Galeta Reef, 17 Feb. 1971, A.A. Reimer, coll. (7.5–13.8 mm long, 1.0– 1.5 mm wide, cephalic cage 2.0– 5.5 mm long, 48–56 chaetigers). Fourteen complete small specimens, and two anterior fragments (USNM-66367), partially dried-out, Galeta Reef , 5 Oct. 1970, A.A. Reimer coll. Brazil. Two specimens ( MNHN- 884 ) , one complete and an anterior fragment, RV Calypso, Stat. 6, Rocas Island , 7 m, 17 Nov. 1961 (complete without dorsal shield, 13.5 mm long, 1 mm wide, cephalic cage 6.5 mm long, 44 chaetigers) .

Description. Syntype (AMNH-1990) complete, partially dehydrated, most chaetae broken ( Fig. 5A); body cylindrical, swollen anteriorly (up to chaetiger 17), tapering posteriorly into a cylindrical thin tail; 17 mm long, 1.2 mm wide, cephalic cage 4 mm long, 48 chaetigers. Tunic thin, no sediment particles adherent to papillae; body papillae short, rounded, arranged in two irregular rows per chaetiger dorsally ( Fig. 5B), becoming one single row ventrally; posterior chaetigers with long interramal papillae.

Cephalic hood not exposed. Anterior end features based on other specimens (LACM-AHF-2524, USNM-66367). Cephalic hood partially exposed in one syntype, short, margin papillated. Prostomium low; eyes large, coalescent, dark brown. Caruncle short, not dividing the branchial plate; median keel low, lateral ridges elevated, slightly darker than the median keel. Palps longer than branchiae; palp keels low, rounded ( Fig. 5F).

Branchiae cirriform, sessile on a branchial plate, arranged in a single row separated by the nephridial lobes; distal row with four larger filaments, decreasing in size laterally; two other smaller branchial filaments, arranged as a marginal row. Sometimes an additional pair of short, thin branchial filaments in the ventral corners. Nephridial lobes as thick as medium-sized branchiae.

Syntype with cephalic cage as long as ¼ body length. Chaetigers 1–2 involved in the cephalic cage; chaetae arranged in a short ventrolateral line, 2–3 noto-, 4–5 neurochaetae per bundle.

Anterior dorsal margin of first chaetiger with a trilobed low projection; chaetigers 1–2 with longer papillae. Chaetigers 1–2 short, chaetiger 3 longer. Sand cemented shield damaged in syntypes; dorsal, apparently poorly defined, reaches chaetiger 4–5 ( Fig. 5E), better defined in non-type specimens. Chaetal transition from cephalic cage to body chaetae abrupt; transition hooks in chaetigers 3–6. Falcate simple hooks present from chaetiger 7. Gonopodial slits in chaetiger 5, short, oval, non-papillated, marginally darker lobes or spots ( Fig. 5D) (in one syntype, and in some mature females from Panama) .

Median notochaetae arranged in a tuft, about 1/6 as long as body width, 1–2 per ramus, few remaining multiarticulate capillaries, articles long. Neurochaetae multiarticulate capillaries in chaetigers 1–2, chaetigers 3–6 with pseudocompound transition hooks ( Fig. 5H, I), falcate simple hooks from chaetiger 7, 2–3 anteriorly, subdistally swollen, mostly 4 along median chaetigers ( Fig. 5J), 2–3 in posterior chaetigers, arranged in transverse rows.

Posterior end tapering to a rounded lobe; pygidium with anus terminal, without anal cirri.

Variation. As indicated for S. caribea , there is some darker, ventral pigmentation along the first few chaetigers in the Caribbean specimens; however, in S. dubia the pigmentation extends along a shorter region than in S. caribea , being up to three chaetigers and most frequently restricted to the ventral side of the ‘lebenshole’ or body opening for the extension of the anterior end.

Remarks. Semiodera dubia ( Treadwell, 1929) n. comb., belongs in a group defined by having 2–3 rows of papillae, smooth integument and four neurohooks per bundle in median chaetigers, which also includes S. blakei n. sp. and S. tovarae n. sp. As stated above, S. blakei differs from the two other species because it has neurohooks from chaetiger 6 (as opposed to chaetiger 7), and because it has large papillae over anterior chaetigers, each with a lanceolate shape (as opposed to being smaller and round). Then, S. dubia is more closely allied to S. tovarae n. sp. They differ because in S. dubia the dorsal shield is not projected laterally, and the neurochaetae in median chaetigers are subdistally swollen, whereas in S. tovarae the shield is laterally projected and its neurochaetae are tapered.

Treadwell (1929:9) stated that his materials were deposited as paratypes, which should be referred to as syntypes, since a holotype was not designated. There seems to be a discrepancy on the branchial filaments of S. dubia ; Treadwell illustrated 6 marginal branchiae, and Hartman found 10, at least basally arranged in two rows. Branchial size diminishes laterally and the smallest ones may have been overlooked by Treadwell , since there are 8 filaments in the dorsal row. The ventral row has a single pair of branchiae, which together with the two large nephridial lobes would make the 10 filaments that Hartman found. The specimens from Panama were contracted; one of them was dissected to study the anterior end, and in another specimen, some median and posterior chaetigers were cut to observe the interramal papillae .

Distribution. Florida to Panama, in shallow water mixed bottoms.