Cossura, Webster & Benedict, 1887

Zhadan, Anna, 2015, Cossuridae (Annelida: Polychaeta: Sedentaria) from Australian and Adjacent Waters: the First Faunistic Survey, Records of the Australian Museum 67 (1), pp. 1-24 : 9-10

publication ID	https://doi.org/ 10.3853/j.2201-4349.67.2015.1639
persistent identifier	https://treatment.plazi.org/id/2B16878E-FF8E-D60B-FE87-FF2DC01FB382
treatment provided by	Carolina
scientific name	Cossura
status

Treatment

Cossura View in CoL sp. cf. ginesi

Liñero-Arana & Díaz-Díaz, 2010

Figs 5 View Figure 5 , 6 View Figure 6

Cossura ginesi LiñeroArana & DíazDíaz, 2010: 791 View in CoL , figs 1, 2.

Type locality. North of the Paria Peninsula, Venezuela, 10°41'27"N 63°15'33"W GoogleMaps .

Material examined. Queensland. 1 specimen, Ports Survey CRIMP Ports Integration Project Cairns, Wharf 12 (16°52'S 145°49'E), W.30833; 11 specimens, Shoalwater Bay , Triangular Islets (22°23'S 150°31'E), coll. Lewis & Forsyth, W. 202744; 16 specimens, Calliope River , Gladstone (23°51'S 151°10'E), W.43728; 1 specimen, Halifax Bay , near mouth of Althaus creek (19°10'S 146°37'E), depth 2 m, 852C2, Feb. 1985, coll GoogleMaps . Queensland Nickel, W. 43332; 10 specimens, Halifax Bay, near mouth of Althaus creek (19°10'S 146°37'E), depth 2 m, 852C3, coll GoogleMaps . Queensland Nickel, W. 43341 .— New South Wales. 1 specimen, Foster NSW 2280, south east end of Yahoo Island, Wallis Lake (32°15'05"S 152°30'05" E), grab, depth 3.4 m, mud + dead shells, 24.03.2003, RV Baragula, coll. P.B. Berents, S.J. Keable, R. T. Johnson, W. 42864 GoogleMaps .

Description. All specimens studied incomplete, with 20–33 chaetigers, 4–6 mm in length; body width about 500 µm. 9–11 thoracic chaetigers but without clear border between body regions ( Fig 5A,C View Figure 5 ). Borders between segments can be more or less distinct depending of relaxation and condition of worm. Chaetigers 1–2 dorsally without clear borders, often swollen ( Figs 5F,H View Figure 5 , 6B,C View Figure 6 ). Chaetigers 3–9 often biannulated, with chaetae-bearing annuli wider and laterally swollen ( Figs 5E View Figure 5 , 6A–C View Figure 6 ). In chaetigers 1–4 chaetae located in anterior part of segments, in chaetigers 4–9 in the middle, beginning from chaetiger 10 close to posterior border ( Figs 5B,C,F,H View Figure 5 , 6B,C,E,F View Figure 6 ). Segments becoming longer in the abdominal region. Branchial filament arising from posterior border of chaetiger 2 ( Figs 5F View Figure 5 , 6B,C View Figure 6 ). Anterior part of the body often swollen dorsally anteriorly from branchial filament ( Figs 5F View Figure 5 , 6B,C View Figure 6 ).

Prostomium from conical to trapezium-shaped, with anterior extension, represented by small semicircular lobe ( Fig. 5B View Figure 5 ) to two well-developed lobes with anterior notch between them, sometimes looking like lateral horns ( Figs 5H View Figure 5 , 6B,C View Figure 6 ). Nuchal organs represented by oval ciliated pits located on lateral side of the prostomium ( Fig. 6C,D View Figure 6 ). Both prostomium and peristomium having secondary furrows subdividing them so the prostomial-peristomial border not clear ( Figs 5H View Figure 5 , 6B,C View Figure 6 ).

Chaetiger 1 with uniramous parapodia, all the next segments bearing biramous parapodia with widely arranged rami ( Figs 5F,G View Figure 5 , 6C View Figure 6 ). All chaetae are hirsute capillaries; arranged in two rows, especially clear in anterior chaetigers. Thicker chaetae are located in anterior row, thinner ones in posterior. First chaetiger bears two thicker chaetae in anterior row and 3–4 thinner ones in posterior; next 8–10 neuropodia bear two very thick brown curved chaetae (10.3–18.0 μm in thickness), widened in middle part, with distal end long thread-like in anterior row in more dorsal position, and four thinner capillaries in posterior row and more ventrally ( Figs 5G View Figure 5 , 6E View Figure 6 ). Notopodia with three thick (but thinner than in neuropodia) chaetae in anterior row and more ventrally, and four thin capillaries posteriorly and dorsally ( Fig. 6E View Figure 6 ). Beginning from chaetiger 11–12 difference in thickness becoming less, all chaetae more or less similar capillaries, up to 10 per ramus ( Fig. 6F,G View Figure 6 ).

Oocytes fulfilling body cavity observed in two specimens from Queensland, Shoalwater Bay, Triangular Islets (W.202744). Posterior end unknown.

Remarks. Specimens investigated here are very similar with Cossura ginesi LiñeroArana & DíazDíaz, 2010 described from Venezuela waters and having anterior extensions of the prostomium. This character is unique among cossurids that usually have conical or rounded prostomium. In Australian worms these extensions is poorly developed and sometimes clear median notch is developed at the end of the prostomium; whereas in Venezuela worms prostomial extensions forms welldefined horns and there is no median notch. Other similarities are two very thick curved chaetae with long thin tips in anterior neuropodia and a comparatively small number of anterior (thoracic) segments (15–16 in C. ginesi and 9–11 in Australian specimens). It is not clear whether differences are due to intraspecific variability or Australian worm represent a new species.