Pseudobranchiomma emersoni Jones, 1962.

Radioles with or without radiolar flanges, serrated or smooth. Some species with paired compound eyes along radioles. Four rows of vacuolated cells supporting the radioles; a multicellular supporting axis of the radiolar appendages of the dorsal lips. Ventral sacs located outside the radiolar crown. Dorsal margins of collar separated from the faecal groove by a wide gap and without “pockets”. Segmental eyespots between the noto- and neuropodia. Spine-like chaetae arranged in oblique rows in the inferior thoracic fascicles. Thoracic companion chaetae absent. Well-developed conical abdominal neuropodia with chaetae arranged in C-shaped fascicles.

There is no apparent morphological synapomorphy supporting Pseudobranchiomma. The monophyly of the genus Pseudobranchiomma has not been tested prior to this study. The group has been defined by a combination of homoplastic characters: presence of radiolar flanges (shared with Stylomma and some Bispira species but absent in P. longa (Kinberg, 1867)); ventral sacs located outside the radiolar crown (shared with Bispira, Branchiomma and Sabella); dorsal margins of the collar separated from the faecal groove by a wide gap and without “pockets” (shared by Bispira, Stylomma and some species of Branchiomma); and absence of thoracic companion chaetae (shared with Branchiomma and Sabellastarte) (e.g. Knight-Jones 1994, Nogueira and Knight-Jones 2002, Nogueira et al. 2006). It has been suggested that the colour pattern of the crown, consisting of transverse yellow and purple bands, could be another diagnostic feature for the genus (Nogueira et al. 2006), but this feature is also very common in Sabellastarte species (e.g. Capa et al. 2010). The monophyly of Pseudobranchiomma is herein also questioned. Morphological data analysis recovers the group as paraphyletic, and the scarcity of molecular data gathered for the present study does not allow us to properly assess monophyly.

Australia: Queensland: AM W.36365, (1 spec.), Heron Island, First Point, North Heron Reef, 23°25'48"S, 151°55'48"E, in coral rubble, 13 m, 12 Nov 2009.

Ten pairs of short flat radiolar serrations evenly distributed along entire length of radioles. RRadiolar eyes absent. Small gap between anterior thoracic ventral shields and neuropodial tori. Thoracic and abdominal uncini with five transverse rows of teeth surmounting main fang. Radiolar crown with wide purple band at base, irregular transverse purple bands on radioles and flanges and yellow band on distal end of radioles. Body pale with distinct interramal eyespots and purple pigment spots on thorax and dorsally on abdomen.

Gravid female, incomplete; body measuring 20 mm long and 2 mm wide, with seven thoracic (Fig. 2D) segments. Crown 8 mm long, slightly involuted ventrally at base, with 17 radioles on each side, connected by an inconspicuous membrane, nearly 1/8^th of length of radioles. Radioles with pinnules of constant length along radioles (Fig. 2B, C), shorter distally; tips of radioles as long as pinnules or shorter. Radiolar flanges present, with around 10 short, flattened, flap-like serrations along entire length of radioles (Fig. 2B, C). Radiolar eyes absent. Dorsal lips with tapered radiolar appendages, almost as long as three thoracic segments, with dorsal lamellae attached to base of adjacent radioles. Dorsal pinnular appendage absent. Four rows of vacuolated cells basally supporting radioles. Ventral lips and parallel lamellae present, with prominent ventral sacs directed outside of the radiolar crown (Fig. 2D–F). Collar with wide dorsal gap, margins fused to end of first chaetiger (Fig. 2F); lateral collar margins smooth, just covering junction of crown and thorax (Fig. 2E, F). Ventral lappets large, subtriangular, non-overlapping (Fig. 2D). Ventral shields conspicuous, first shield trapezoidal in shape, but appearing as an anterior Y-shaped and a posterior W-shaped segment when stained with methyl green; shields not in contact with or indented by ventral tori in all thoracic chaetigers (Fig. 2D). Interramal eyespots conspicuous. (Fig. 2D, E). First chaetiger with narrowly hooded chaetae. Rest of thoracic chaetigers with about six superior elongate narrowly hooded chaetae (Fig. 3C) and 16 shorter spine-like inferior chaetae arranged in two rows (Fig. 3D). Neuropodial uncini with approximately five rows of teeth above the main fang, well developed breast and short handle (Fig. 3A). Abdominal chaetigers with narrowly hooded superior chaetae and shorter spine-like chaetae (Fig. 3E) appearing broadly hooded depending on angle (Fig. 3F). Notopodial uncini similar to thoracic ones (Fig. 3B). Pygidium missing. Eggs are present in thorax and anterior abdominal segments.

Figure 2. 

Pseudobranchiomma cf. P. emersoniAM W.36365; photographs of preserved specimen; A Radiolar crown, dorsal view B Detached radiole C Detail of base of crown and single radiole D Anterior segments, ventral view (crown detached) E Same, lateral view F Same, dorsal view. vl, ventral lappet; vs, ventral sacs; white arrows, serrations of radiolar lateral flanges; black arrow, gap between ventral shields and thoracic tori.

Figure 3. 

Line drawings of chaetae and uncini of Pseudobranchiomma species in Australia; A–F Pseudobranchiomma cf. P. emersoni G–L Pseudobranchiomma cf. P. orientalis M–T Pseudobranchiomma pallida sp. n. U–Z, A1 Pseudobranchiomma cf. P. schizogenica; A Thoracic uncinus B Abdominal uncinus C Superior thoracic chaeta D Inferior thoracic chaeta E, F Inferior abdominal chaetae G Thoracic uncinus H Abdominal uncinus I Superior thoracic chaeta J Inferior thoracic chaeta K, L Inferior abdominal chaetae M, N Thoracic uncini O Abdominal uncinus P, Q, R Inferior thoracic chaetae S Superior abdominal chaeta T Inferior abdominal chaeta U, V Thoracic uncini W Abdominal uncinus X, Y Superior thoracic chaetae Z, A1 Inferior thoracic chaetae. Scale bars: A–F = 2 µm; G–L = 4 µm; M–T = 2 µm; U–Z, A1 = 2 µm.

Body pale with distinct interramal eyespots of same size in thorax and abdomen (Fig. 2D, E) and purple pigment spots sparsely distributed on thorax (Fig. 2D–F) and dorsally on abdomen. Crown with wide purple band at base (Fig. 2A) and approximately 10 irregular, purple bands (some incomplete transversely) evident on outer side of radioles and flanges; only one yellow band present on distal end of radioles. Dorsal margins of collar (Fig. 2F) and ventral lappets (Fig. 2D) with scattered spots.

Pseudobranchiomma emersoni Jones, 1962 is a species that was originally described from Jamaica, but has also been reported from the Cape Verde Islands (according to Knight-Jones 1994, p.197, although not verified since) and Florida, USA (Nogueira et al. 2006). It is characterised by a combination of features: up to ten pairs of short flat serrations along each radiole, 5–6 rows of teeth over the main fang in thoracic uncini, a branchial crown that has narrow irregular bands of purple colour (or “splotches”), with often a reduced number of thoracic segments (as few as four, indicating evidence of imperfect regeneration after asexual reproduction), large interramal eyespots, and a collar ventral shield that is trapezoidal in shape (according to Tovar-Hernández and Dean 2014). The Australian specimen, when stained with methyl green, displayed a similar staining pattern on the collar ventral shield as that described for Pseudobranchiomma schizogenica Tovar-Hernández and Dean, 2014, although the authors state that this feature differentiates P. schizogenica from P. emersoni and P. orientalis (Tovar-Hernández & Dean, 2014). Although these latter authors also describe the interramal spots of P. emersoni as “large”, Knight-Jones and Giangrande’s (2003) illustration of the type specimen indicates small spots, so there is some ambiguity regarding this feature, particularly as this can be a subjective assessment. The Australian specimen described above concurs in most respects with P. emersoni, particularly the flattened step-like form of the radiolar serrations, the irregular colour pattern of the branchial crown and the possession of large interramal eyespots, but because there are slight differences (e.g. 4–5 rows of teeth of the thoracic uncini; the similarity of staining pattern of the ventral shields with P. schizogenica), and the lack of multiple specimens, we prefer to reserve definite identification until there can be examination of more specimens from Australia, and comparison with the type specimens. The report of this species by Russell and Hewitt (2000) in the ports of Darwin, Northern Territory, is not confirmed, as material from this survey, deposited at the NTM, was examined, and specimens labelled as “P. emersoni”, were found to be P. cf. P. schizogenica.

Species known from Jamaica, Florida (USA), Cape Verde Islands, and now Heron Island, Queensland, Australia, where it inhabits coral rubble at shallow depths.

Australia: Queensland: AM W.10308 (1 on microscope slide), Calliope River, 23°49'S, 151°13'E, 8 Oct 1975; AM W.37752 (4 specs.), Calliope River, 23°51'S, 151°10'E, 1974; AM W.37204 (1 on 2 SEM pins), same site and date; AM W.32677 (1 spec.), Karumba, 17°29'S, 140°50'E, beam trawl, 1 m, Aug 2000; AM W.37749 (2 specs), Karumba port, Berth 2, 17°29'S, 140°50'E, scraping from pylon, 3m, Aug 2000; AM W.37751 (1 spec.), Karumba, 17°29'S, 140°50'E, benthic sled, 15m, Aug 2000; AM W.32678 (1 spec), Cairns, Wharf 8, 16°53'60"S, 145°48'E, scraping from wharf pile, 7 m, 20 Nov 2001; AM W.32679 (2 specs), Weipa, Lorim Point Wharf, 12°40'S, 141°57'E, scraping from wharf pile, 3 m, Oct 1999; AM W.37750 (1 spec.), Weipa, Lorim Point Wharf, 12°40'S 141°57'E, scraping from wharf pile, 7m, Oct 1999. Northern Territory: NTM W017392 (3 specs), Darwin Harbour, Iron Ore Wharf, 12°28'21"S, 130°50'34"E, scrapings from wharf pile, 5–10 m, 1998.

Ten to 25 serrations evenly distributed along entire length of radiolar flanges, Radiolar eyes absent. Thoracic ventral shields and uncinal tori separated by a small gap. Thoracic and abdominal uncini with 5–7 transverse rows of teeth over main fang. Radiolar crown with broad purple basal band, and approximately 20 transverse purple pigment bands along radioles, interspersed with orange and thin white bands; body with few pigment spots and with small, indistinct interramal eyespots.

Specimens 5–24 mm long (with 12 mm long crown on longest specimen), 3 mm maximum width; 7–8 thoracic and 50 abdominal chaetigers. Crown strongly involuted ventrally (Figs 4A, 5A), almost forming circle, with 10–30 radioles on each side. Radiolar flanges with conspicuous serrations from end of basal membrane to tip (Figs 4C, D, 5B), 10–25 per radiole (Figs 4A, C, 5A). Radiolar eyes absent. Pinnules decreasing in size distally (Fig. 4B). Radioles supported basally by 6–10 rows of vacuolated cells. Basal membrane as long as one to two thoracic segments, 1/7th–1/8th length of radioles. Dorsal lips with long, thin and pointed radiolar appendage 1/3rd length of crown (Fig. 4A, E). Pinnular appendages absent. Ventral lips nearly half of length of dorsal lips, pointed in shape, attached to 5th or 6th ventral radiole, with large and conical ventral sacs, as long as two thoracic chaetigers, located outside crown (Fig. 4A, F). Collar with wide dorsal gap and dorsal margins reaching end of the first chaetiger; lateral margin of collar smooth, covering junction between crown and thorax with short ventrolateral notch present as oblique incision (Figs 4F, 5A). Ventral lappets large, sub-triangular and rounded tips directed laterally (Fig. 4A, F). First segment as long as remaining thoracic segments. Ventral shields conspicuous, with large intersegmental incisions; thoracic ventral shields similar in width, but some specimens with first two shields wider than subsequent ones. First shield trapezoidal in shape, but appearing as an anterior Y-shape and posterior W-shaped segment when stained with methyl green. Small gap between ventral shields and thoracic tori (Fig. 4A, G). Interramal eyespots small, inconspicuous (Fig. 4G, H). First thoracic notopodia with around 10 superior elongate narrowly hooded chaetae (Fig. 5C) and around 12 short, narrowly hooded chaetae arranged in two rows (Fig. 5C). Subsequent thoracic notopodia with superior elongate narrowly hooded chaetae (Figs 3I, 5D) and shorter spine-like inferior thoracic chaetae arranged in two rows (Figs 3J, 5D). Well-developed thoracic tori with uncini decreasing in size ventrally; uncini with five rows of small teeth over main fang, occupying about half its length, breast well developed, long neck and short handle (Figs 3G, 5E, F). Abdominal chaetigers with superior narrowly hooded chaetae (Fig. 3K) and inferior spine-like chaetae (Figs 3L, 5H). Abdominal uncini with several rows of teeth above main fang, breast well developed and short handle (Figs 3H, 5G). Pygidium bilobed. Tube thick with muddy particles attached. One specimen (AM W.32679) with eggs in mid abdominal chaetigers, others with eggs in thorax.

Figure 4. 

Pseudobranchiomma cf. P. orientalisAM W.32677, AM W.32679: Photographs. A Anterior end, ventral view B Detached radiole C Detail of lateral radiole, mid length D Detail of base lateral radiole E Detail of radiolar crown base with dorsal radiolar appendages F Detail of radiolar crown base with ventral sacs G Anterior thoracic parapodia H Posterior abdominal segments. dra, dorsal radiolar appendages; vs, ventral sac; black arrows, interramal eyespots.

Figure 5. 

Pseudobranchiomma cf. P. orientalisAM W.37204: Scanning electron micrographs A Anterior end, lateroventral view B Detail of lateral flanges serrations C Notopodia, first thoracic segment D Notopodia, fifth thoracic segment E Uncini, second thoracic segment F Uncini, fifth thoracic segment G Posterior abdominal uncini H Neuropodia, mid abdominal segment I Posterior end, ventral view. Scale bars: A = 1 mm; B, I = 100 µm; C, D, G, H = 20 µm; E = 3 µm; F = 10 µm.

Preserved specimens may have few pigment spots on body, with some pigment on end of the faecal groove and dark patches on bases of ventral lappets, internally. Crown with pigments units coinciding with serrations, about 20 thin transverse purple-brown bands on outer side of radioles and flanges, continuing in one or two pinnules, and orange and white bands in between, which may fade (Fig. 4A–F). Longitudinal purple-pigmented midline at bases of each radiole and at ventral and dorsal base of crown may be present (Fig. 4A). Dorsal lips sometimes pigmented; ventral sacs conspicuous due to their white colour (Fig. 4A, F).

These Australian specimens are identified as P. cf. P. orientalis, a species originally described from Hong Kong. Knight-Jones reviewed, and illustrated the types (previously unpublished but shared with MC and reproduced here as Fig. 6) with characters not illustrated in the original description such as the details of the radiolar flanges serrations (Fig. 6A–C), details of the anterior and posterior parts of the body in different views, with special attention to the shape of thoracic ventral shields (fig. 6D–G), and the shape of the parapodia in the thoracic and abdominal segments (Fig. 6H, I) that help confirm the identifications. The Australian specimens share most diagnostic features with the original description and drawings, as well as subsequently published supplementary information about the types (McIntosh 1885, Knight-Jones 1994, Tovar-Hernández and Dean 2014). These are: the number and shape of the serrations in the radiolar flanges (Figs 4C, D, 6A–C), presence of a small gap between the ventral shields and the adjacent thoracic tori (Figs 4G, 6E), and the presence of ventrolateral notches in the collar (Figs 4F, 6E, F) (McIntosh 1885, Knight-Jones 1994). There are some variations however from the reported descriptions, including the presence of interramal eyespots in the thorax, albeit small and inconspicuous, and the staining pattern of the first ventral shield which, as with P. cf. P. emersoni, yielded the same result as that reported by Tovar-Hernández and Dean (2014) for P. schizogenica, even though this was a feature used to differentiate the latter species from P. orientalis and P. emersoni. So, because of these differences we prefer to qualify a definite identification of these Australian specimens as P. orientalis. Pseudobranchiomma orientalis was reported in some ports in Northern Territory, Australia (Russell and Hewitt 2000), and after examination of these specimens, it is established that they are P. cf. P. orientalis, as described above. Should further sampling and molecular data confirm the status of Pseudobranchiomma orientalis in Australia, it is reasonable to suppose that it has been translocated from Asian waters, especially if its restricted range, in ports and harbours, is verified.

Figure 6. 

Pseudobranchiomma orientalis Type BMNH 85.12.1.393. Line drawings by Phyllis Knight-Jones. A–C Second dorsal radiole from different views D Holotype, divided in two, and partially covered by the tube, lateroventral view E Base of crown and anterior thoracic chaetigers, ventral view F Same, lateral view G Same, dorsal view H Thoracic parapodium I Abdominal parapodium. Scale bars: A–C = 1 mm; D = 2 mm; E–G = 1 mm; H–I = unknown.

Pacific Ocean (Hong Kong, Australia: Northern Territory and Queensland).

Australia, Queensland. Holotype AM W.36366, Heron Island, First Point, North Heron Reef, 23°25'48"S, 151°55'48"E, coral rubble, 13 m, 12 Nov 2009.

Approximately six pairs of low serrations evenly distributed along radiolar flanges. Radiolar eyes absent. Thoracic ventral shield separated from uncinal tori. Uncini with three transverse rows of teeth over main fang. Radiolar crown with broad purple band at base and distal third with wide yellow band, rest colourless white bands; body pale with distinct interramal eyespots.

Specimen incomplete; body measuring 10 mm long (including crown) and 1 mm wide, with six thoracic and more than 18 abdominal segments (Fig. 7A, B). Crown 4 mm long, slightly involuted at base ventrally, with nine radioles on each side, connected by inconspicuous membrane extending 1/7th–1/8th of radiolar length, or length of one thoracic segment (Fig. 7D). Radiolar flanges present, with about six low serrations along entire length of radioles (Fig. 7C). Radiolar eyes absent (Fig. 7A–C). Radioles supported basally by four rows of vacuolated cells. Radiolar pinnules similar in length, shorter distally; tips of radioles as long as pinnules or shorter (Fig. 7C). Dorsal lips with tapered dorsal radiolar appendages, about as long as two thoracic segments, with dorsal lamella attached to base of adjacent radiole. Dorsal pinnular appendages absent. Ventral lips and parallel lamellae present with prominent ventral sacs directed outside of radiolar crown (Fig. 7A, B, D). Collar margins separated dorsally by wide gap, with dorsal margins fused to end of first chaetiger (Fig. 7F), lateral collar margins smooth, just reaching junction of crown and thorax (Fig. 7E). Ventral lappets, sub-triangular and non-overlapping (Fig. 7D). Ventral shields of first two segments slightly shorter than other thoracic segments (Fig. 7E). First shield trapezoidal in shape, but appearing as anterior Y-shape and posterior W-shaped segment when stained with methyl green. Ventral shields not in contact with or indented by tori (Fig. 7E). Interramal eyespots conspicuous (Fig. 7D, E). First chaetiger with narrowly hooded chaetae arranged in two rows. Rest of thoracic chaetigers with about five superior narrowly hooded chaetae and 8–10 shorter inferior spine-like thoracic chaetae with hood similar width to shaft (Fig. 3R) appearing in some cases as broadly hooded (Fig. 3P, Q). Neuropodial uncini with three rows of teeth above main fang, well-developed breast and short handle (Fig. 3M, N). Abdominal chaetigers with narrowly hooded superior chaetae (Fig. 3S) and spine-like inferior chaetae (Fig. 3T). Notopodial uncini similar to thoracic ones (Fig. 3O). Pygidium missing.

Figure 7. 

Pseudobranchiomma pallida sp. n. AM W.36366: Photographs. A Whole specimen, ventral view B Whole specimen, lateral view C Lateral radioles D Detail of base of radiolar crown and anterior segments E Anterior thoracic segments, ventrolateral view F Anterior end, dorsal view. vl, ventral lappet; vs, ventral sac; white arrows, serrations of radiolar lateral flanges; black arrow, gap between ventral shields and thoracic tori.

Body pale with distinct interramal eyespots (Fig. 7B, D, E) and pigment on dorsal margins of collar (Fig. 7F). Crown with broad purple band at base and distal third with wide yellow band, rest colourless (Fig. 7A–C). Ventral sacs and lappets colourless (Fig. 7D).

Pseudobranchiomma pallida sp. n. is characterised by the remarkable colour pattern of the radiolar crown with a purple basal band and yellow radiolar tips, instead of the characteristic bands, as well as the absence of pigment spots on the body. This species belongs to the artificial Group A of Knight-Jones and Giangrande (2003), members of which possess serrations along the radiolar flanges (Table 3). The number of serrations (4–6) resembles that of P. paraemersoni and P. schizogenica (with 3–4 and 6–11 respectively), while other larger species bear nine or more (Table 1 of Tovar-Hernández and Dean 2014). The new species differs from P. paraemersoni and P. schizogenica in the morphology of the uncini, with three transverse rows of teeth over the main fang (4–5 and four rows respectively, for P. paraemersoni and P. schizogenica; Tovar-Hernández and Dean 2014).

Australia (Queensland, Heron Island).

This species is named after its colour pigmentation, pale compared with other Pseudobranchiomma species, and completely lacking pigment spots on the body.

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. P. 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.

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.

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.

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.

Figure 8. 

Pseudobranchiomma cf. P. schizogenica. AM W.36368, AM W.36369. Photographs. A Anterior end, lateral view B Detail of base of crown and anterior segments, ventral view C Detail of lateral radiole D Anterior thoracic segments, lateral view E Anterior thoracic segments, dorsal view F Anterior thoracic segments, dorsal view. dra, dorsal radiolar appendages; vl, ventral lappet; vs, ventral sac; white arrows, serrations of radiolar lateral flanges.

Figure 9. 

Pseudobranchiomma cf. P. schizogenica. Scanning electron micrographs. A–F specimen from Queensland AM W.37205 G–L specimen from Western Australia AM W.37203. A Whole specimen, lateral view B Base of crown, dorsal view with dorsal lips and radiolar appendages C Notopodia, second thoracic segment D Uncini, third thoracic segment E Posterior abdominal neurochaetae F Uncini, posterior abdominal segment G Detail of lateral radiole with serrations in flanges H Notopodia, first thoracic segment I Uncini, fifth thoracic segment J Notopodia fourth thoracic segment K Neuropodia, mid abdominal chaetigers L Posterior abdominal uncini. Scale bars: A = 200 µm; B, G = 100 µm; C = 20 µm; D, F, I, L = 2 µm; E, H, J, K = 10 µm.

Figure 10. 

Pseudobranchiomma cf. P. schizogenica from Hawaii AM W.37206, AM W.37207: Scanning electron micrographs. A Detail of radiolar flanges serrations B Base of crown and anterior segments, ventral view C Lateral radioles D Anterior segments, dorsal view E Notopodia, first thoracic segment F Notopodia, second thoracic segment G Uncini, third thoracic segment H Neuropodia, posterior abdominal segment I Posterior abdominal uncini J Posterior end, ventral view (pygidium regenerating) K Posterior end, dorsal view. vl, ventral lappets; vs, ventral sac. Scale bars: A = 20 µm; B, C, J, K = 100 µm; D = 200 µm; E, H = 10 µm; F = 20 µm; G, I = 2 µm.

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. 8A–E), above which there is a pale band followed by dark purple and orange bands (Fig. 8A–E). Pairs of dark purple pigment spots on outer edge of radioles form 4–6 distinct bands along length of radioles (Fig. 8A–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 pigmentation. 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.

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 P. 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 P. cf. P. 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 P. schizogenica). Similarly, P. emersoni shares some features with P. cf. P. 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.

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).