Branchiomma (Knight-Jones, 1994)

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 : 6-7

Key to species of Branchiomma from tropical American coasts

1 Width of stylodes less than half width of radiolar rachis; shapes digitiform, sub­digitiform or strap­like........................................................................................................... 2

­ Width of most or a few stylodes as broad (or broader) than width of rachis; shapes either tongue­like or with distal parts broader than their bases..................................... 5

2 Large, plump body with thorax about as long as wide; stylodes sub­digitiform with a few pairs in middle of radiole twice length of others (macrostylodes); ventral collar lappets fleshy with rounded apices; thoracic uncinus showing a single crest tooth in side view ....................................................................... B. nigromaculatum (Figs 1 & 2)

­ Small, slim body with thorax mostly longer than wide; stylodes digitiform or straplike; ventral collar lappets membranous and sub­triangular; thoracic uncinus showing two or three crest teeth in side view.............................................................................. 3

3 Thorax usually shorter than wide; stylodes digitiform with even gradation of lengths throughout radiole (no macrostylodes); short overlapping ventral lappets; thoracic torus showing nearly three crest teeth in side view ..................... B. curtum ( Figs 5 & 8 )

­ Thorax longer than wide; stylodes digitiform or strap­like; ventral lappets long or short; thoracic torus showing two crest teeth in side view............................................ 4

4 Two or three pairs of strap­like macrostylodes in distal half of radiole, three or four times as long as neighbouring and other digitiform stylodes; radiolar eyes small, a third of width of radiolar skeleton; ventral collar lappets small and well separated ...... .............................................................................................................. B. bairdi ( Fig. 3 )

­ Stylodes strap­like with even gradation of lengths throughout radiole (no macrostylodes); radiolar eyes large, larger than the width of internal radiolar skeleton; ventral collar lappets long, reaching bottom of first ventral shield when reflexed..................... .......................................................................................... B. illifei sp. nov. ( Figs 7 & 8 )

5 Most stylodes with distal parts broader than their bases, often fluted giving foliose appearance, one of each pair often shorter than the other (around the middle of the radiole); large plump body with thorax wider than long; ventral lappets sub­triangular, fleshy and overlapping in reflexed position ................. B. coheni sp. nov. ( Figs 6 & 8 )

­ Two or three pairs of tongue­like stylodes (length: breadth ratios 3:1 & 5:1) (macrostylodes) in distal half of radiole, with neighbouring and other pairs mostly small and digitiform; pairs of stylodes same length; body slim with thorax longer than wide; ventral lappets sub­circular ................................................................... B. conspersum ( Fig. 4 ).

Figures

FIGURE 3. Branchiomma bairdi lectotype (A–D, H–K) and Branchiomma species A. (E–G): A) radiole; B) whole worm in ventral view; C) anterior in dorsal view; D) anterior in lateral view; E–F) second radiole on left; G) anterior in ventral view; H) thoracic uncinus; J) abdominal uncinus; K) inferior thoracic chaeta. Scale bars: A 2 mm, B–D, G 3 mm, E–F 2.5 mm, H–J 30 m, K 95 m.

FIGURE 4. Branchiomma conspersum lectotype (posterior missing and tear on left side): A–C) dorsal, ventral, and lateral views respectively of thorax and adjacent areas; D) lateral anterior, showing crown length; E) inferior thoracic chaeta; F) superior thoracic chaeta; G) thoracic uncinus; H, J) radioles. Scale bars: A–B 2.2 mm, C 1.5 mm, D 2 mm, E–F 255 m, G 20 m, H 5.5 mm, J 2.25 mm.

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.