Pseudobranchiomma cf. schizogenica Tovar-Hernandez & Dean, 2014

Capa, Maria & Murray, Anna, 2016, Combined morphological and molecular data unveils relationships of Pseudobranchiomma (Sabellidae, Annelida) and reveals higher diversity of this intriguing group of fan worms in Australia, including potentially introduced species, ZooKeys 622, pp. 1-36 : 16-22

Taxon classification Animalia Sabellida Sabellidae

Pseudobranchiomma cf. schizogenica Tovar-Hernandez & Dean, 2014 Figures 3 U–Z, A1, 8, 9, 10

Pseudobranchiomma schizogenica Tovar-Hernández & Dean, 2014: 936-945, figs 1-5.

Material examined.

Australia: Queensland: AM W.36369 (1 spec.), Heron Island, Sykes Reef, 23°25'57"S, 152°02'02"E, coral rubble, 15 m, 13 Nov 2009; AM W.36368 (1 spec.), Heron Island, First Point, 23°25'56"S, 151°56'02"E, coral rubble, 13 m, 12 Nov 2009; AM W.36364 (1 spec.), Sykes Reef, 23°25'57"S, 152°02'02"E, coral rubble, 15 m, 13 Nov 2009; AM W.37753 (2 specs) same locality and date; AM W.32676 (1 spec.) Abbott Point, near Bowen, 19°53'S, 148°05'E, pylon scraping, 8 Jun 1998; W.36978 (1 spec. used for sequencing), Lizard Island, MacGillivray Reef, deep reef slope, 14°39'25"S, 145°28'22"E, coral rubble, 30 m, 4 Sep 2010; AM W.41160 (1 spec.), Reef 14-141 south of South Direction Island, 14°42'31"S, 145°31'53"E, in coarse coral rubble, 15 m, 26 Aug 2010; AM W. AM W.43938 (>25 specs), south east of Lizard Island, reef on north west side of North Direction Island, 14°44'36"S, 145°30'20"E, from sand, 10 m, 15 Aug 2013; AM W. 47698 (1 spec.), Lizard Island group, reef on north eastern side of South Island, 14°42'13"S, 145°27'37"E, coral rubble, 5-12 m, 21 Aug 2013. Northern Territory: AM W.37754 (3 specs) Darwin, Lee Point, 12°20.0'S, 130°58.3'E, dead coral washings, 3 m, 11 Jun 1993; ex NTM W017392 (10 specs), Darwin Harbour, Iron Ore Wharf, 12°28'21"S, 130°50'34"E, scrapings from wharf pile, 5-10 m, 1998, originally identified as Pseudobranchiomma orientalis ; NTM W017392 (part, 2 specs), Darwin Harbour, Iron Ore Wharf, 12°28'21"S, 130°50'34"E, scrapings from wharf pile, 7 m,16 Aug 1998, originally identified as Pseudobranchiomma cf. Pseudobranchiomma emersoni . Western Australia: AM W.37756 (13 specs) Ningaloo Reef, 22°45'19"S, 113°42'40"E, sponge and bryozoa, 15-17 m, 19 May 2009; AM W.37757 (3 specs), Ningaloo Reef, 22°45'19"S, 113°42'40"E, sandstone, 15-17 m, 19 Jun 2009; NTM W018246 (>50 specs) Ashmore Reef, inner lagoon, encrusting sponges, 15 m, 01 Jun 2002, originally identified as Pseudobranchiomma orientalis .

Comparative material.

Hawaii: AM W.35576 (1 spec.), AM W.35577 (1 spec), AM W.35578 (1 spec.), AM W.37206, (1 spec. on SEM pin), AM W.37207 (1 spec. on SEM pin), all from Oahu, Coconut Island, 21°25'48"N, 157°57'43", epifauna growing on pier, 1 m, 4 Sep 2008.

Diagnosis.

Three to six pairs of digitiform radiolar serrations evenly distributed along entire length of radioles. Radiolar eyes absent. Thoracic ventral shields and neuropodial tori separated by a gap. Thoracic and abdominal uncini with about four transverse rows of teeth surmounting main fang. Radiolar crown with transverse dark purple and orange bands at base and 4-6 irregular purple bands along radioles. Body pale, or with some purple patches; large interramal eyespots decreasing posteriorly.

Description of Australian specimens.

Specimens range from 3-19 mm long, 0.2-1 mm wide, with 4-7 thoracic and numerous abdominal segments. One complete specimen from AM W.43938 measures 19 mm in length and 1 mm maximum width, including crown 4 mm long, with 6 thoracic and>80 abdominal chaetigers. Body thin and cylindrical. Crown length varies between 1.5 and 4 mm. Radiolar crown lobes semicircular at base, with about nine radioles on each side, connected by basal membrane equivalent to length of at least one thoracic chaetiger (Figs 8D, 9A, B) or 1/8th of radiolar length. Radioles with serrated radiolar flanges, 3-6 digitiform serrations along entire length of radioles (Figs 8C, 9A, G, 10C). Radiolar eyes absent. Pinnules of constant length along radioles, shorter distally; tips of radioles as long as pinnules or shorter. Radioles supported basally by four rows of vacuolated cells. Dorsal lips with tapered dorsal radiolar appendages, about as long as 3-4 thoracic segments (about one third of radiolar crown length), with dorsal lamella attached to base of adjacent radiole (Fig. 9B). Dorsal pinnular appendages absent (Fig. 9B). Ventral lips and parallel lamellae present, with prominent ventral sacs directed outside of the radiolar crown (Figs 9A, 10B). Collar with dorsal margins separated by wide gap (Figs 8E, 9B, 10D), margins fused to end of first chaetiger; laterally, collar margins smooth, only just reaching junction of crown and thorax (Figs 8E, 9A). Ventral lappets large, sub-triangular, non-overlapping (Figs 8A, B, 9A, 10B). Ventral shields conspicuous (Fig. 8B), first shield trapezoidal, but when stained with methyl green, appears separated into anterior Y-shaped half and posterior W-shaped half; second shield trapezoidal, following shields rectangular. All ventral shields not in contact with or indented by tori. Interramal eyespots conspicuous (Fig. 8A, D). First chaetiger with narrowly hooded chaetae arranged in two rows (Figs 9H, 10E); remaining thoracic chaetigers with about five superior elongate narrowly hooded chaetae and around nine shorter spine-like inferior chaetae (Figs 3X, Y, 9C, J, 10F) with hood as wide as shaft. Neuropodial uncini with about four rows of teeth above main fang (Figs 3U, V, 9D, F, 10G) well-developed breast and short handle with rounded knob on base (Fig. 3U, V). Abdominal chaetigers with narrowly hooded superior chaetae and spine-like inferior chaetae with hood about half width of shaft (Figs 3Z, A1, 9E, K, 10H). Notopodial uncini very similar to thoracic ones (3W, 9F, L, 10I). Pygidium bilobed.

Colour pattern.

Body pale with large interramal eyespots (Fig. 8A), decreasing in size gradually towards posterior; small dark purple pigment spots sparsely distributed (Fig. 8A, B, E) over entire body. Some specimens have purple patches on ventral shields as well as further along ventrum and dorsum. Crown with purple pigmentation in basal membrane (Fig. 8 A–E), above which there is a pale band followed by dark purple and orange bands (Fig. 8 A–E). Pairs of dark purple pigment spots on outer edge of radioles form 4-6 distinct bands along length of radioles (Fig. 8 A–E), coinciding with number of serrations along radioles. On some radioles pigmentation extends to base of one or two pinnules. Dorsal margins of collar (Fig. 8E) and ventral lappets (Fig. 8B) have some purple pigmen tation. Preserved specimens usually pale with few brown patches on collar and lappets, crowns with some bands of brown pigment, and may have brown longitudinal lines on base of crown. Conspicuous interramal eyespots are maintained after preservation.

Remarks.

This species, originally described from the Gulf of California, is characterised by having radioles with short and digitiform serrations along the entire radiolar length, ventral shield of collar trapezoidal and divided into two halves, thoracic superior chaetae and abdominal chaetae with hoods narrower than shafts and thoracic inferior chaetae spine-like with hoods as wide as shafts ( Tovar-Hernández and Dean 2014). The specimens found in several localities around the northern Australian coastline and in Hawaii match this diagnosis and additionally share the same colour pattern (four to six repeated pigment units, resembling transverse bands and a wider orange band on the base of radioles) and the number of teeth over the main fang (four). There are, however, some differences between these specimens and the original description of Pseudobranchiomma schizogenica , including one feature considered to be diagnostic of this species: the lateral margins of the collar, because they are oblique, do not always cover the anterior peristomial ring (Fig. 8E); there are also fewer flange serrations per radiole (up to six) in the Australian specimens, even the largest ones, compared with the Gulf of California specimens (6-11). The specimens also somewhat resemble Pseudobranchiomma paraemersoni Nogueira, Rossi and Lopez, 2006, from Brazil, a species that also shares a similar number of thoracic segments (between 5 and 7), large interramal eyespots, and the typical transverse bands of pigments in radiolar crown, but differs from Pseudobranchiomma cf. Pseudobranchiomma schizogenica by having fewer number of flange serrations per radiole (3-4) and inferior thoracic spine-like chaetae with hood twice as wide as shaft (hood only as wide as shaft in Pseudobranchiomma schizogenica ). Similarly, Pseudobranchiomma emersoni shares some features with Pseudobranchiomma cf. Pseudobranchiomma schizogenica , but differs from it by the irregular branchial crown pigment pattern, the greater number of rows of teeth above main fang in thoracic uncini (5-6), greater number of radioles (14), and the non-differentiated first ventral shield.

Distribution.

Southern Gulf of California (Mexico), northern Australia and Hawaii. This species is associated with coral rubble and epifauna attached to hard substrates in shallow depths (0-15 m).