Terebella verrilli Holthe, 1986

Londoño-Mesa, Mario H. & Carrera-Parra, Luis F., 2005, Terebellidae (Polychaeta) from the Mexican Caribbean with description of four new species, Zootaxa 1057, pp. 1-44 : 33-35

Terebella verrilli Holthe, 1986

Figures 8 F–K

Material examined: Mexican Caribbean: ECOSUR TERE­3 (3) Tulum (20°12’01’’N 87°25’50.1’’W), 24 Feb. 1986. (1) E3M5T1 Nichupté, Cancún (21°06’11.6’’N 86°47’21.1’’W), 20 Apr.1988. (1) E7M1T1 Nichupté, Cancún (21°06’11.6’’N 86°47’21.1’’W), 6 Jul. 1988. (1) R/V “Edwin Link”, sta. 2784, Punta Chacom (Xocox) (18°46’42’’N 87°34’05’’W), 24 Aug. 1990. (2) QR4 21 Mar. 1992, (2) QR5 Playa Aventuras (20°20’15.5’’N 87°20’31.7’’W), 22 Mar. 1992. (1) Cozumel Island (20°23’45.1’’N 86°51’53.5”W), 5 Jun. 1995. (1) E16 Buenavista (18°30’42’’N 87°45’30’’W), 1 Oct. 1996. (1) A16 Majahual (18°40’09.6’’N 87°43’01.4’’W), 29 May 1997. (2) Punta Nizuc (21°02’11.7’’N 86°46’44.2’’W), 1 Sep. 1997. (1) Xahuayxol (18°30’15’’N 87°45’32’’W), 2 Jun. 1998. (3) Contoy Island (21°30’8.4’’N 86°47’45.3’’W), 10 Jun. 1999, in Ircinia sp. (1) Majahual (18°40’09.6’’N 87°43’01.4’’W), 30 Nov. 2000. (2) Majahual (18°40’09.6’’N 87°43’01.4’’W), 1 Dec. 2000, on algae, 2 m. (2) Majahual (18°40’09.6’’N 87°43’01.4’’W), 19 Jan. 2001. (3) Sol y Mar Hotel, Majahual (18°44’14’’N 87°41’20’’W), 19 Jan. 2001. (2) Nichupté canal, Cancún (21°06’11.6’’N 86°47’21.1’’W), 18 Aug. 2002.

Description: Specimen complete, light brown on preserved material, with 124 segments, 44 mm long; thorax 2.2 mm wide ( Figures 8 F–G). Abdomen with midventrally grooved. Long and thick tentacles, with small spots at both sides of the groove. Tentacular membrane well developed laterally, dorsally narrower. Eyespots concentrated laterally on tentacular membrane, with spots well separated from each other, sometimes with narrow belt of eyespots across the membrane. Upper lip with folded free edge projecting forwards; lower lip thin, projected as a tongue. Lateral lappets absent. Three pairs of equal­sized branchiae, branched, with long filaments, starting from segment 2; second pair more laterally, closer to notopodia, than other pairs; branchia with a short stalk. Fourteen pairs of nephridial papillae present; first pairs as a long tube, dorsal to the bases of second pair of branchiae ( Figure 9 G), remaining 13 pairs, starting from segment 6, rounded, as wide as the bases of notopodia and dorsal to them. Twelve ventral shields present, starting from segment 2; first three shields fused, shields on anterior thoracic segments short and broad, becoming progressively longer and narrower towards posterior thorax. Eighty­two notopodia, separation between thorax and abdomen not clearly. Notopodia short, starting from segment 4. Notochaetae of two types; on anterior segments of two sizes; of which long chaetae 1.5 times as long as the short chaetae, chaetae medially bilimbate and distally denticulate (each limb distally hirsute) ( Figure 8 H–I); posterior notochaetae also variable in size, distally curved, trumpet­like, without limbs, distally denticulate ( Figure 8 J). Neuropodia starting from segment 5, with uncini arranged in single rows on segments 5 to 10, in double rows from segment 11, arranged in face to face position. Neuropodia elevated from midabdomen; rows of uncini well separated. Thoracic uncini with dental formula MF:10–12:8–10: ( Figure 8 K), main fang well developed, anterior process projected as a heel, posterior process as long as the main fang, with evident subrostral process; occipitium straight or slightly curved. Pygidium with dorsal anus, large, with 10 anal papillae.

Var ia t io n: Thorax with variable number of notochaetigers, from 25 to 118. The total number of segments in all specimens complete revised varies from 42 to 124 segments.

Remarks: Holthe (1986b) replaced the name Leprea rubra with Terebella verrilli because it was preoccupied.

Distribution: Northwestern Atlantic Ocean, Mexican Caribbean.

Material examined: Mexican Caribbean: Holotype ECOSUR 0 0 57 (1) Punta Herradura, Quintana Roo, Mexico (18°32’23’’N 87°44’32’’W), 30 Nov. 2000, 80 m. Paratype LACM­AHF (2) same data of holotype.

Etymology: This species is dedicated to Damhnait McHugh, for her great contributions to the knowledge of Polychaeta Terebellidae .

Description: Holotype complete, mature female, body light brown on preserved material, small and fragile; with 82 segments, 32 mm long; thorax 2 mm wide ( Figures 9 A–B). Midventral abdominal grooved absent. Many eggs in the coelom of posterior thoracic region. Tentacles thin, dark brown. Tentacular membrane dorsally reduced, ventrally visible. Numerous small, dark eyespots, placed laterally on the tentacular membrane. Upper lip with rounded free edge, reduced and often folded, about conspicuous and swollen lower lip, as wide as the base of the upper lip. Lateral lappets absent. Three pairs of branchiae, discontinuous, branched, placed on segments 3, 4, and 7; third pair larger than the others, first pair the shorter (half as long as third pair), branchiae with short stalks, long branches, arranged in three levels of ramification, and long digitated tips. Nine pairs of nephridial papillae, low and small, starting from segment 6, placed between noto­ and neuropodia; nephridial pore sometimes visible. Fourteen ventral shields present, starting from segment 1; first and second shields swollen, tapering along posterior thorax, strongly reduced posteriorly. Thorax not well defined because of the large number of pairs of notopodia (holotype 40, paratype 74). Notopodia starting from segment 4. Notochaetae ( Figure 9 C), long with distal oblique and serrated part; sometimes curled; chaeta diminishing in length within the same fascicle. Neuropodia from segment 5; uncini arranged in single row on segments 5–9, in double rows on segments 10–77, in face to face position, in single row on segments 78–82. Thoracic and abdominal uncini similar to each other. Uncini with dental formula MF:1:4:4 ( Figure 9 D), with rounded upper subrostrum, well­developed subrostral process, without evident appendix; long lower subrostrum, weakly convex and ending by conspicuous button­shaped anterior process, with thin filament; basis rounded with pointed heel­like posterior process; occipitium long, curved and convex; capitium with three lines of teeth. Pygidium with 15 anal papillae. Tube made by small coarse sand, foraminifera, small shells, calcareous algae and sponge spicules, attached to a very weak and transparent membrane. Found on the base of black coral ( Anthipathes sp.).

Remarks: This species is included in the genus Terebellobranchia as it has a non segmental arrangement of branchiae, notopodia starting on segment 4 and neuropodia starting on segment 5 as in the type species T. natalensis Day, 1951 ( Natal, South Africa). The second species described in the genus is T. hugonis Rullier, 1972 ( New Caledonia). T. mchughae sp. nov differs from T. natalensis in the distribution of the branchiae, the former has branchiae on segments 3, 4, 7, and the latter has branchiae on segments 3, 7, 13. T. hugonis has the same segmental distribution of branchiae as T. mchughae sp. nov; but this species was described having notopodia from segment 3 and neuropodia from segment 4; furthermore, this species has capillary chaetae serrated with posterior pectinate twisted end on middle and posterior notopodia ( Rullier, 1972:146 fig. 35C), while T. mchughae sp. nov has notopodia with capillary chaetae serrated. The starting position of notochaetae and neuropodia of T. hugonis differs from the other two species, but this could be an overlooked counting of segmentation. A review of the type material of T. hugonis will be necessary to elucidate the question, but this is beyond the scope of this study.

Type locality: Punta Herradura, Southern Mexican Caribbean.

Distribution: Restricted to the type locality.

Figures

FIGURE 8. Pista cf. quadrilobata: A. Lateral view; B. Ventral view; C. Chaetae from segment 15; D. Uncinus from segment 5; E. Uncinus from segment 8. Terebella verrilli: F. Ventral view; G. Anterior end in dorsal view with nephridial tube; H. Chaetae from segment 10; I. Chaeta from segment 10; J. Chaetae from segment 50; K. Uncini from segment 10. Scale bars: A, B 1 mm; C, D, E, I, J 0.02 mm; F 1 mm; G 0.5 mm; H 0.05 mm; K 0.01 mm.

FIGURE 9. Terebellobranchia mchughae: A. Lateral view; B. Ventral view; C. Chaetae from segment 5; D. Uncinus from segment 12. Scale bars: A 1 mm; B 2 mm; C 0.05; D 0.01 mm.