Tetreres oscari, Chávez-López, 2022

Chávez-López, Yessica, 2022, New species of sabellariids (Annelida: Sabellariidae) from the Caribbean Sea and the Gulf of Mexico, European Journal of Taxonomy 831, pp. 109-148 : 142-145

Tetreres oscari sp. nov.

urn:lsid:zoobank.org:act:080B2BD8-DA8B-4E30-B51C-AC79F6ED37DA

Figs 20–21

Diagnosis

Outer paleae oblong, compressed with acute tips. Inner paleae slightly oblong, smooth, with blunt tips. Five tentacular filaments. First thoracic segment with a pair of long tapered cirri.

Etymology

This species name is after my brother Oscar Chávez-López. It is a noun in the genitive case ( ICZN 1999, Art. 31.1.2).

Material examined

Holotype FLORIDA STRAIT • complete spec.; southwest of Marquesas Keys; RV Gerda , stn 968; 24°17′ N, 82°34′ W; depth 378 m; 2 Feb. 1968; UMML-22.1197 .

Paratypes FLORIDA • 1 spec.; southeastern Miami ; RV Gerda , stn 265; 25°40′ N, 80°00′ W; depth 332 m; 28 Mar. 1964; UMML-22.1198 • 1 spec. (body fragmented in two parts after the operculum); same collection data as for preceding; ECOSUR-305 .

Additional material

NORTH ATLANTIC – Florida Strait • 1 dry spec.; southeastern Key West ; RV Gerda , stn 15; 25°05′ N, 80°00′ W; depth 288 m; 30 May 1962; UMML-22.1199 .

Description

BODY. Holotype complete (UMML-22.1197) 12 mm long, 0.5 mm wide, four parathoracic segments, 22 abdominal segments, 4 mm caudal peduncle ( Fig. 20 ).

OPERCULUM. Opercular disc oblique ( Fig. 20A–B, F ). Outer paleae arranged in semicircles, 22 paleae on each lobe ( Fig. 20F ). Inner paleae in short ventral line on each inner margin of opercular lobes, three paleae on each lobe ( Fig. 20F ). Outer paleae pale yellow, oblong, compressed, 1 mm long. Blade three times as long as wide, with thecae transverse, compact; tips acute ( Fig. 21A–B ). Inner paleae pale yellow, slightly oblong, smooth, tips blunt ( Fig. 21C–D ). Opercular stalk pale yellow, three times as long as wide ( Fig. 20B–D ). Opercular papillae in one row peripheral to outer paleae, 11 papillae on each lobe. Papillae conical and tapered, 3–4 times as long as wide ( Fig. 20F ). One pair of yellow nuchal hooks, long, robust, with short limbation, tips falcate ( Figs 20B , 21E–G ). In lateral view, nuchal hook distally curved at angle of ~135° ( Fig. 21E ). Palps pale yellow, broken. Tentacular filaments simple, pale yellow, grooved; three tentacles on left lobe, five tentacles on right ( Fig. 20D ). Median organ small, conical ( Fig. 20B ).

THORAX. First thoracic segment with long, triangular-shaped lateral lobe, and capillary chaetae. Second segment with three lateral lobes, and paired branchiae; first lobe after branchiae three times as long as other ones ( Fig. 20A–B ).

PARATHORAX. With four segments, all with paired branchiae. Notopodia with four lanceolate chaetae and six capillary chaetae ( Fig. 21H ). Neurochaetae capillary.

ABDOMEN. Abdominal segments yellowish. Last ten abdominal segments colorless, translucent. Neurochaetae capillary, ornamented with irregular thecal laminar extension ( Fig. 21I ). Notopodia with series of uncini with eight rows of teeth ( Fig. 21J ). Caudal peduncle colorless, translucent. Anus with two rigid white balls of sediment ( Fig. 20A ).

Variation

Specimens incomplete 7–10 mm long, 0.4–0.5 mm wide, seven abdominal segments. Only holotype complete. Operculum with 19–22 outer paleae per lobe, 3–5 inner paleae per lobe. Opercular papillae 8–12 per lobe. Only holotype with three tentacular filaments on left lobe; rest of specimens with five per lobe. Lateral cirrus of second thoracic segment 2–3 times as long as other cirri.

Tubes

With foraminiferans (UMML-22.1198, UMML-22.1199, Fig. 21K ).

Remarks

Tetreres oscari sp. nov. is very similar to T. varians ; however, both species can be distinguished by the morphology of the outer paleae, the length of the thoracic cirri, and mainly by the number of tentacular filaments.

The outer paleae of T. oscari sp. nov. have acute tips, whereas the paleae of T. varians are illustrated with mucronate tips ( Augener 1906: pl. 7 fig. 131; Kirtley 1994: fig. 12.10.3a, d–f). The number of outer paleae also differs among these species. According to Hartman (1944: 333), the type specimen of T. varians has 25–30 outer paleae per lobe, whereas T. oscari sp. nov. has 19–22 per lobe. Further, T. oscari sp. nov. is characterized by two lateral lobes on the second thoracic segment, and one of them is three times as long as the other, whereas T. varians has three lateral lobes of similar size ( Kirtley 1994: fig. 12.10.1a–b).

The number of tentacular filaments is the most obvious character. Although the number of tentacular filaments of T. varians has not been described, according to the drawings of Augener (1906: pl. 7 fig. 130) and Kirtley (1994: fig. 12.10.1a–b), T. varians has about 10 thin tentacular filaments on each lobe, whereas T. oscari sp. nov. has only five broad ones.

Distribution

Southeast Florida, 288–378 m depth ( Fig. 22 ).

Figures

Fig. 20. Tetreres oscari sp. nov., holotype (UMML-22.1197). A. Complete specimen, dorsal view. B. Anterior region, dorsal view. C. Anterior region, lateral right view. D. Anterior region, ventral view. E. Last abdominal segments. F. Opercular crown, upper view. Abbreviations: c2 = cirri 2nd thoracic segment; ip = inner paleae; mo = median organ; nh = nuchal hooks; opa = opercular papillae; op = outer paleae. Numbers indicate the tentacular filaments. Arrows indicate gametes. Scale bars: A = 1 mm; B–D = 0.5 mm; E–F = 0.2 mm.

Fig. 21. Tetreres oscarisp. nov., holotype (UMML-22.1197). A–B. Outer palea.C-D. Inner palea.E. Nuchal hook, lateral view. F. Nuchal hook, ventral view. G. Tip of nuchal hook. H. Parathoracic notochaetae. I. Abdominal parapodium.J. Uncini. K. Tube. Abbreviation: Li = limbation. Numbers indicate the rows of teeth. Scale bars: A, D, G–I = 100 µm; B = 50 µm; C, E–F = 200 µm; J = 20 µm; K = 2 mm.

Fig. 22. Localities for studied specimens. A. Caribbean Sea and the Gulf of Mexico. B. South Florida. C. Southeastern Bahamas. The crosses indicate type localities of species previously recorded in the tropical Western Atlantic.