Branchiomma

Capa, María & Murray, Anna, 2015, A taxonomic guide to the fanworms (Sabellidae, Annelida) of Lizard Island, Great Barrier Reef, Australia, including new species and new records, Zootaxa 4019 (1), pp. 98-167 : 109-110

Branchiomma sp.

( Fig. 3 C–E)

Branchiomma sp. D. Capa et al. 2013.

Material examined. Queensland, Lizard Island: AM W.197053 (4), lagoon, dropoff between Bird Islet and South Island, 14°42′S, 145°28′E, prepared coral block, 9 m, Apr 1978; AM W.35631, bommie near entrance to lagoon, 14°41′13′′S, 45°27′56′′E; AM W.40721, 14°41′34′′S, 145°28′2′′E, 2 m, coral rubble, 11 Apr 2008; AM W.40897 (5), Turtle Beach, 14°39′9′′S, 145°27′3′′E, 9.5 m, 7 Sep 2010; AM W.40899 (3), North Direction Island, lagoon patch reef, 14°44′43′′S, 145°30′18′′E, 8.5–25 m, 4 Sep 2010; AM W.40924 (3), North Direction Island, 14°44′43′′S, 145°30′18′′E, coral rubble, 8 m, 26 Aug 2010; AM W.40929, fringing reef on east side of North Direction Island, 14°44'43"S, 145°30'18"E, coral rubble, 1 m, 26 Aug 2010; AM W.40931 (4), south of South Direction Island, 14°42′31′′S, 145°31′53′′E, coral rubble, 15 m, 26 Aug 2010; Outer Barrier: AM W.36494 (2), Yonge Reef, 14°35′59′′S, 145°37′52′′E, coral rubble and sand, 2 m, 12 Feb 2009; AM W.40901, Yonge Reef, 14°34′22′′S, 145°37′8′′E, sand & coral rubble, 25 m, 10 Sep 2010; AM W.40933 (6), Turtle Beach, 14°39′8′′S, 145°27′4′′E, coral rubble, 1 m, 30 Aug 2010; AM W.40926, lagoon, 14°41′13′′S, 145°27′18′′E, coral rubble, 1 m, 31 Aug 2010; AM W.40928 (5), MacGillivray Reef, 14°39′23′′S, 145°29′31′′E, coral rubble, 22 m, 29 Aug 2010; AM W.43876, MI QLD 2329; AM W.43877, MI QLD 2335; AM W.43881, MI QLD 2331; AM W.43932, MI QLD 2342; AM W.43936, MI QLD 2348; AM W.44207, MI QLD 2370; AM W.44212, MI QLD 2359 (5); AM W.44365, MI QLD 2359 (10); AM W.44366, MI QLD 2401 (3).

Description of material examined. Specimens up to 8 mm long and 1.7 mm wide. All specimens with 4–6 thoracic ( Fig. 3 C–E) and numerous abdominal chaetigers. Live specimens with reddish irregular transverse bands alternating with white bands; radiolar eyes bright orange ( Fig. 3 C–E). Body bright green with few dark and white spots ( Fig. 3 C–E). Dark interramal eyespots on thoracic and abdominal chaetigers, conspicuous in small specimens. Preserved specimens with radiolar crown with irregular purple-brown pigment, the pigment along the body fades and only a few spots, if any, remain on anterior thoracic chaetigers. Radiolar crown with basal lobes semicircular. Dorsal and ventral basal flanges absent. Basal membrane reduced. Radiolar flanges absent. Paired stylodes present, a generic diagnostic feature in Branchiomma and unique feature among sabellids, digitiform, about the width of rachis, except for one or two pairs in the distal half of radioles that are longer and flattened (in larger specimens, Fig. 3 E). Paired compound radiolar eyes, alternating with stylodes along radioles ( Fig. 3 C–E). Dorsal lips with long radiolar appendages; ventral lips and parallel lamellae present; ventral sacs outside radiolar crown. Posterior peristomial ring collar with well separated dorsal margins, ventral lappets separated by a midventral incision. Glandular ridge on chaetigers 1 or 2 absent. Ventral shields conspicuous, in contact with neuropodial tori ( Fig. 3 C, E); first one with m-shaped anterior margin. Collar chaetae with superior notochaetae narrowly-hooded, inferior notochaetae spine-like arranged in oblique rows. Following thoracic chaetigers with notopodia as conical lobes ( Fig. 3 E), with superior notochaetae narrowly-hooded, inferior notochaetae spine-like. Thoracic neuropodial uncini avicular, with two rows of teeth over main fang, occupying about half of main fang, breast well developed, handle very short. Companion chaetae absent. Abdominal neuropodia as conical lobes with superior narrowly-hooded neurochaetae and inferior spine-like neurochaetae arranged in a C-shaped pattern. Uncini avicular, with three rows of teeth above main fang, breast well developed, handle very short. Pre-pygidial abdominal depression absent. Bilobed pygidium with eyespots on both sides. Pygidial cirrus absent. Leathery tubes covered with mud on exposed anterior end.

Remarks. This species was characterised and defined by molecular markers as Branchiomma sp. D (in Capa et al. 2013). Some of the diagnostic morphological features of this species are the presence of a posterior peristomial ring collar with wide separated dorsal margins, the digitiform stylodes along radioles, with one or two pairs that are about twice as long as their neighbours and flattened and thoracic uncini with two rows of small teeth over the main fang. Colour is also characteristic: orange and white-banded radiolar crown, with the proportion of the two pigments varying among specimens (e.g., Fig. 3 C, E), and a bright green body with a few bright white and dark red-brown spots. The genus is in need of a worldwide revision, considering that several species, like this one, could have been translocated out of their natural distribution range ( Capa et al. 2013). It is difficult to know if the species described herein has already been described or if it should be described as new. Many specimens examined are regenerating anterior or posterior ends ( Fig. 3 C) or possess bifurcated posterior ends, indicating they can reproduce asexually by scissiparity, but also have 4-6 thoracic segments, suggesting that they may all be juvenile.

Habitat. Coral rubble and other hard substrates with algae and epifauna, 1– 15 m.

Distribution. Hawaii, Australia (Western Australia and Queensland).

Figures

FIGURE 3. A, B. Branchiomma bairdi, preserved specimens. A. Anterior end, ventral view, showing the radiolar crown, thorax and anterior abdominal chaetigers; B. Detail of base of radiolar crown, showing stylodes (black arrows) and paired compound eyes (white arrows) and anterior thoracic chaetigers, with collar dorsal margins widely separated; C – E. Branchiomma sp., live specimens; C. Whole specimen, ventral view, regenerating posterior end; D. Radiolar crown with paired radiolar eyes (white arrows) and stylodes (black arrows); E. Specimen with four thoracic chaetigers, anterior end, ventral view. Photographs: A – B by Eunice Wong.