Pseudobranchiomma cf. orientalis (McIntosh, 1885)

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 : 10-14

Taxon classification Animalia Sabellida Sabellidae

Pseudobranchiomma cf. orientalis (McIntosh, 1885) Figures 3 G–L, 4, 5

? Dasychone orientalis McIntosh, 1885: 498-500, pl. LII, fig 5, Pl.XXXA, figs 19-21, pl. XXXIXA, fig 4.

? Pseudobranchiomma orientalis : Knight-Jones 1994: fig. 4k; Russell and Hewitt 2000: 69, 89; Tovar-Hernández and Dean 2014: 936, table 1.

Material examined.

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.

Diagnosis.

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.

Description of Australian specimens.

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, 1/7 th– 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.

Colour pattern.

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. 4 A–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).

Remarks.

These Australian specimens are identified as Pseudobranchiomma cf. Pseudobranchiomma 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. 6 A–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. 6 D–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, 6 A–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 Pseudobranchiomma cf. Pseudobranchiomma emersoni , yielded the same result as that reported by Tovar-Hernández and Dean (2014) for Pseudobranchiomma schizogenica , even though this was a feature used to differentiate the latter species from Pseudobranchiomma orientalis and Pseudobranchiomma emersoni . So, because of these differences we prefer to qualify a definite identification of these Australian specimens as Pseudobranchiomma 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 Pseudobranchiomma cf. Pseudobranchiomma 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.

Distribution.

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