Branchiomma coheni, Tovar-Hernández & Knight-Jones, 2006

Tovar-Hernández, María Ana & Knight-Jones, Phyllis, 2006, Species of Branchiomma (Polychaeta: Sabellidae) from the Caribbean Sea and Pacific coast of Panama, Zootaxa 1189 (1), pp. 1-37 : 24-27

Branchiomma coheni sp. nov.

Figures 6A–M , 8A , 9E–G , 10D , 11C

Material examined

Type material: Holotype [ LACM­AHF POLY 2131 ] Panama, Punta Culebra , Naos, 08° 54.7’ N, 79° 31.8’ W, LH02­688E, Coll. L. Harris, Apr. 30, 2002 from intertidal area of large boulders and rocks buried in sand and associated tide pools, with smaller rocks often with smooth, tough sponge on sides and bottom . Paratypes [ LACM­AHF POLY 2132 ] (4), [ LACM­AHF POLY 2133 ] (3), [ ECOSUR 0051 ] (1), sample location and date as for holotype .

Non­type material: NW Australia, Original material B. galei ( Augener, 1914: fig. 16, pt. 1, figs 16–17 as Dasychone ) [ZMUH V8281, PK­J]. New Material [MAT­H]: Panama [ECOSUR] Gatun Locks, Balboa, Coll. S. I. Salazar, May 28, 2002, intertidal (5); Balboa Yacht Club, 08° 56.3’ N, 79° 33.3’ W, Coll. S. I. Salazar, May 30, 2002, intertidal (4); Fuerte Rodman, Balboa, Coll. S. I. Salazar, May 31, 2002, intertidal (28); Diablo Spinning Club, Balboa, 08° 57.8’ N, 79° 34.2’ W, Coll. S. I. Salazar, June 5, 2002, intertidal (30); May 30, 2002, intertidal (15). [LACM­AHF] Punta Culebra, Naos, 08° 54.7’ N, 79° 31.8’ W, LH02­688E, Coll. L. Harris, Apr. 30, 2002 (1); Balboa Yacht Club, 08° 56.3’ N, 79° 33.3’ W, LH02­637E; Coll. L. Harris, May 30, 2002 (1); Diablo Spinning Club, Balboa, 08° 57.8’ N, 79° 34.2’ W, LH02­678E, Coll. L. Harris, Apr. 30, 2002 (1).

Description

The following description is based mainly on the holotype with data in parentheses for the paratypes.

Specimens large, with body without crown 17 mm long, thorax 3 mm long, 4.5 mm wide (3–4.5). Body green mottled with small brown spots ( Figs 6A–B ), and interramal dark spots, larger on first thoracic segments and smaller in posterior region. Radiolar crown long (half of the body length), 9 mm length, united at the base by short web or membrane, with longitudinal bands of dark brown spots below each web. About 25 pairs (20–28) of radioles, each banded with green olive bands (occupying space of three pinnules). Bands dark brown in some specimens and one orange band between each pair of eyes, only from the median region of the crown to the anterior end. Radioles with apinnulate tips, as long as equivalent space of two pinnules ( Fig. 6F ). Basal stylode unpaired, medium length, tongue­like, as wide as rachis. Stylodes: 15 pairs [s, s, s, s, M, M, L, L, L, L, L, L, L, s, s]. Stylodes with fairly even gradation of length along radiole (macrostylodes absent); basal pairs tongue­like ( Figs 9F–G ), more distal pairs of stylodes wider subdistally, sometimes rounded, sometimes bilobed ( Fig. 5F–G ) or with very uneven distal margins ( Fig. 9G ). Each new pair of stylodes (near tip of radiole) digitiform and showing asymmetric development ( Fig. 6G ). Eyes not present between last pair of stylodes, otherwise eyes small, with those from medial and distal regions surrounded by accumulation of pigment cells ( Fig. 6F ); lenses cone­shaped. Dorsal lips long, one half length of radioles, triangular with a distinct orange longitudinal ridge (mid­rib), lateral margin olive­green. Transverse section of dorsal lip showing numerous supporting cells of radiolar appendage (mid­rib), flanked by lamellae; these with blood vessels, without surrounding sheath ( Fig. 6E ). Midline faecal groove deep on first segment forming mounds each side ( Fig. 6A ). Collar well separated dorsally, with ventral lappets rounded, full overlapped ( Figs 6B , 8A ), each one with a big orange spot. Thorax with eight segments. Thoracic tori extending to sides of brown trapezoidal ventral shields. Collar chaetae slender, weakly geniculate ( Fig. 6H ), arranged in compact fascicles. Thoracic notochaetae arranged within each fascicle in irregular, oblique rows of superior and inferior chaetae ( Fig. 10D ); each superior chaeta slender, weakly geniculate ( Fig. 6J ), with knee region slightly wider than shaft; whereas inferior chaetae with knee up to twice as wide as shaft ( Fig. 7K ). Avicular uncini with the crest surmounted by two rows of teeth (side view), occupying one quarter of the crest with three teeth in anterior row and two smaller ones in next row ( Fig. 11C ), and manubrium short ( Fig. 6C ). Abdomen with 49 segments (38–86). Tori smaller than those in thorax. Most fascicles of abdominal chaetae forming compact tufts, with outer chaetae geniculate ( Fig. 6L ), arranged in a thick Cshaped arc around a cluster of capillary chaetae ( Fig. 6M ). Abdominal uncini with short straight manubrium ( Fig. 6D ). Pygidium bilobed. Tube of one paratype containing three small tanaid tubes.

Remarks

Branchiomma coheni clearly differs from B. nigromaculatum , B. bairdi , B. conspersum , and B. curtum , which have either intermittent macrostylodes on the distal half of the radiole or just digitiform stylodes throughout the radiole length. The broad stylodes of B. coheni form a fairly even gradation in size thoughout the length of the radiole as in other Group F species. Branchiomma coheni most closely resembles B. galei ( Augener, 1914: fig. 16, pt. 1, figs 16 and 17 as Dasychone ) of the species in that group. Augener’s type material shows a more even gradation of stylode length throughout the radiole than indicated by his figure (PK­J, pers. obs). B. galei has mainly long broad stylodes, with sides more or less parallel, particularly between the median and subdistal areas of the rachis. The sides of the stylodes of B. coheni , however, rapidly widen towards the tips, giving a foliose appearance somewhat like B. infarctum ( Krøyer, 1856, redescribed by Knight­Jones, 1994) and B. natalensis ( Kinberg, 1867, as Sabella ) (PK­J, pers. obs). Branchiomma infarctum and B. natalensis differ from B. coheni in having thoracic uncini with numerous rows of crest teeth (characteristic of Group E). Another Branchiomma species , with foliose stylodes (and thoracic uncini with numerous crest teeth), is B. violacea Schmarda (1861 , as S abella, Cape of Good Hope, South Africa, but this species also differs from B. coheni in having a bispiral crown and the dorsal collar fused to the sides of the midline faecal groove (Group A).

Type locality Punta Culebra , Naos, Panama, 08° 54.7’ N, 79° 31.8’ W .

Distribution Pacific coast of Panama.

Etymology

This species is named in honour of Dr. Andrew Cohen (San Francisco Estuary Institute), who made possible this expedition to the Panama Channel, and in recognition of his work in biological invasions.

Figures

FIGURE 5. Branchiomma curtum Mexican material: A) body in lateral view; B) thoracic uncinus; C) abdominal uncinus; D) superior collar chaeta; E) superior thoracic chaetae; F) inferior thoracic chaeta; G) superior abdominal chaeta. Scale bars: A 1 mm, B–C 10 m, D–G 0.04 mm.

FIGURE 6. Branchiomma coheni sp. nov. holotype: A) thorax and anterior abdomen in dorsal view; B) thorax in ventral view; C) thoracic uncinus; D) abdominal uncinus; E) dorsal lip in transverse section (bv blood vessels, dl dorsal lip lamellae, c coelom, rs radiolar skeleton); F) radiole end; G) radiole median region; H) collar chaeta; J) superior thoracic chaeta; K) inferior thoracic chaeta; L) inferior abdominal chaeta; M) superior capillary abdominal chaetae. Scale bars: A–B 2 mm, C–D 0.02 mm, E 0.12 mm, F–G 0.2 mm, H–M 0.04 mm.

FIGURE 7. Branchiomma iliffei sp. nov. holotype: A–B) anterior thorax and lower crown in dorsal and ventral views respectively; C) dorsal right radiole, lateral view; D) thoracic uncinus; E) abdominal uncinus; F) superior thoracic chaeta; G) inferior thoracic chaeta; H, J) inferior abdominal chaeta in side and face view respectively; K) superior capillary chaeta from same fascicle. Scale bars: A–B 1 mm, C 0.5 mm, D–E 0.02 mm, F–K 0.01 mm.

FIGURE 8. Anterior thorax in Branchiomma coheni, B. iliffei, and B. curtum. A) B. coheni sp. nov. anterior thorax and lower crown in ventral view; B) B. iliffei sp. nov. collar in dorsal view; C) B. iliffei anterior thorax and lower crown in ventral view; D) B. curtum whole body in ventral view; E) B. curtum thorax and crown in dorsal view. Scale bars: A 285 m, B 200 m, C 1 mm, D–E 250 m.

FIGURE 9. Stylodes of Branchiomma nigromaculatum, B. bairdi, B. coheni, B. curtum, and B. iliffei ECOSUR specimens, mounted in gold for SEM. A–B) B. nigromaculatum stylodes from basal region and medial region; C–D) B. bairdi stylodes from basal region and medial region; E–G) B. coheni sp. nov. unpaired stylodes from base of radiole, paired stylodes from medial region, and from medial to distal region; H, J) B. curtum stylodes from basal region and, medial region; K–M) B. iliffei sp. nov. stylodes from basal region, medial region, and distal region. Scale bars: A, K 50

FIGURE 10. Parapodia of Branchiomma nigromaculatum, B. bairdi, B. coheni, B. conspersum, B. curtum, and B. iliffei ECOSUR specimens, mounted in gold for SEM. A–B) B. nigromaculatum thoracic and abdominal parapodia; C) B. bairdi thoracic parapodium; D) B. coheni sp. nov. thoracic parapodium; E) B. conspersum thoracic parapodium; F) B. curtum thoracic parapodia; G) B. iliffei sp. nov. abdominal parapodium. Scale bars: A 125 m, B 67 m, C, E 83 m, D 50 m, F 33 m, G 40 m.

FIGURE 11. Thoracic uncini of Branchiomma nigromaculatum, B. bairdi, B. coheni, B. conspersum, B. curtum, and B. iliffei ECOSUR specimens, mounted in gold for SEM. A) B. nigromaculatum; B) B. bairdi; C) B. coheni sp. nov; D) B. conspersum; E) B. curtum; F) B. iliffei sp. nov. Scale bars: A 6 m, B–C 10 m, D 5 m, E 5 m, F 4 m.