Branchiomma iliffei, 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 : 27-31

Branchiomma iliffei sp. nov.

Figures 7A–K , 8B–C , 9K–M , 10G , 11F

Material examined

Type material: Holotype [ LACM­AHF POLY 2129 ] Bahamas, Exuma Cays, Basil Minn’s Cave , 23° 28’ N, 75° 45’ W, Sta. 45, LH03­233, in marine entrance pool, algae and sediment scooped up from bottom (strong sulphuric acid odour from black silt), Coll. L. Harris, Jan. 11, 2003 . Paratypes [ LACM­AHF POLY 2130 ] (3), sample location and date as for holotype .

Non­type material: Curaçao [ZMA] V. Pol. 0068.01, Spaansche Water, in mangrove roots, 0–1 m, Coll. C. J. van der Horst, Apr. 3, 1920 (1); V. Pol. 1404, Saint Croix Krausse, lagoon sea side, July 15, 1955, on muddy sand flat with clumps of Rhizophora sp. sea grasses, Cassiopeia sp. , 0–2 m, Coll. P. Wagenaar Hummelinck (4).

Description

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

Body elongate, 19.5 (23–32) mm long without crown, thorax 3 mm long (3.5), 2 mm wide. Body colour dark brown with interramal dark brown spots, small, difficult to distinguish against the background colour of the body. Radiolar crown short (one­quarter of the body length), 6 (8) mm long. Radioles united at the base by short dark green web or membrane, consist of 13 pairs (13–14) with green and maroon bands, each band occupying space of two or three pinnules), and stylodes with inner region maroon. Radioles with apinnulate tips, as long as equivalent space of 10 pinnules. Basal stylode unpaired, medium length, sub­digitiform; stylode width one half of the rachis width. Stylodes: 16 pairs [m, m, m, m, m, l, l, l, l, l, l, l, l, l, l, l], all sub­digitiform ( Fig. 9L ), with long pairs only 1–1.5 times as long the medium ones ( Fig. 9M ); width of those from basal region of radiole one half of the rachis width, as in those of the medial region. Eyes big, near to the radiolar tip, covering whole of side of radiolar rachis ( Fig. 7C ), with those from median and distal region surrounded by an accumulation of pigment cells, and lenses cone­shaped. Dorsal lips short, one­quarter length of radioles, triangular and with a distinct orange longitudinal ridge (mid­rib) with some small dark olive green spots. Midline faecal groove deep on first segment forming mounds each side, collar well separated dorsally ( Figs 7A , 8B ); ventral lappets triangular, not overlapping ( Figs 7B , 8C ). Thorax with eight segments. Thoracic tori extending to sides of green ventral shields ( Fig. 7B ). Collar chaetae slender, weakly geniculate, arranged in compact fascicles. Thoracic notochaetae arranged within each fascicle in irregular oblique rows of superior and inferior chaetae; each superior chaeta slender, weakly geniculate, knee region slightly wider than shaft ( Fig. 7F ); inferior chaetae with knee up to twice as wide as shaft ( Fig. 7G ). Avicular uncini with the crest surmounted by three rows of teeth (side view) occupying one half of the crest with four or five teeth per row ( Figs 7D , 11F ), and with short, curved manubrium ( Fig. 7E ). Abdomen with 65 (66–69) segments. Tori smaller than those in thorax (less than a half its length). Most fascicles of abdominal chaetae forming single compact tufts ( Fig. 10G ), outer chaetae geniculate ( Figs 7K ), arranged in a Cshaped arc around a cluster of more slender shafted capillary chaetae ( Fig. 7K ); number of chaetae per fascicle decreasing gradually towards newer posterior segments. Abdominal uncini with short straight manubrium ( Fig. 7E ). Faecal groove passes around right side of body from the last thoracic segment to second segment of ventral abdomen and on to bilobed pygidium. Tubes made of brown, fine sand.

Remarks

Branchiomma illifei differs from B. nigromaculatum , B. bairdi and B.conspersum in having stylodes of similar shape and size throughout the radiole (lacking macrostylodes). The species differs from Branchiomma curtum (and others in the B. cingulatum group, PK­J pers. obs) in being more elongate, with a longer thorax, and bearing more numerous stylodes, but its most distinguishing character is the remarkable size of its eyes, which take up most of the width of the rachis in side view ( Fig. 7C ).

Type locality Bahamas, Exuma Cays, Basil Minn’s Cave , 23° 28’ N, 75° 45’ W .

Distribution Bahamas and Curaçao.

Etymology

This species is named in honour of Dr. Tom Iliffe (Texas A & M University at Galveston) in recognition of his research on Bahamas.

m, B 25 m, C, E–F, L 67 m, D, G 125 m, H 33 m, J 17 m, M 100 m.

Discussion

Wide geographical distributions of polychaete species, whether or not they are referred to as cosmopolitan, are often suspect. Detailed study usually finds that more than one species is involved. It is less time­consuming to synonymise species, than to spend time studying each in fine detail. The distribution of Branchiomma nigromaculatum given above is now more limited than that in general polychaete literature. The Cape Verde Island records, apparently the only proven ones outside of the West Atlantic tropical waters, could have been distributed by flotsam using the Gulf Stream / North Atlantic current / North equatorial current gyre. However, some species really do have a wide, if not a cosmopolitan, distribution. The wider, somewhat linear distribution of Branchiomma curtum Ehlers from Chile, New Zealand, Cape Verde Islands and Mexico may have been assisted by ballast water from ships.

Figures

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.