Cossura keablei, Zhadan, 2015

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 : 13-15

publication ID	https://doi.org/10.3853/j.2201-4349.67.2015.1639
persistent identifier	https://treatment.plazi.org/id/2B16878E-FF8A-D60E-FE83-FF2DC6B7B159
treatment provided by	Carolina (2021-04-13 16:38:38, last updated by Plazi 2023-11-02 06:05:46)
scientific name	Cossura keablei
status	sp. nov.

Treatment

Cossura keablei View in CoL n. sp.

Figs 9–11 View Figure 9 View Figure 10 View Figure 11

Type locality. Fiji, Suva Harbour.

Type material. Holotype anterior fragment 0.5 mm wide, 8.75 mm long, with 24 thoracic chaetigers; Fiji, Suva Harbour (18°8'S 178°25'E), Oct. 1998, coll. Shirley Mohammed, stn.18 A, W.45623. GoogleMaps

Paratypes 2 specimens, Philippines, west coast of Marinduque Island (13°30'N 121°30'E), Dec. 1996, coll. MARCOPPER staff, Stn. 30, W.27171; 1 complete specimen, SEM pin mount, Philippines, west coast of Marinduque Island (13°30'N 121°30'E), Dec. 1996, coll. MARCOPPER staff, Stn. 30, W.42862 GoogleMaps ; 1 specimen, Fiji, Suva Harbour (18°8'S 178°25'E), Benthic survey, Oct. 1998, coll. Shirley Mohammed, stn.18 A, W.46099 GoogleMaps .

Additional material examined. Philippines. 3 specimens, West coast of Marinduque island (13°30'N 121°30'E), W.27175 GoogleMaps .— Fiji. 3 specimens, stn.19B, Suva & Nadi Harbour, Benthic survey, Oct. 1998, coll. Shirley Mohammed, W. 43358 ; 1 specimen, Suva & Nadi Harbour, Benthic survey, Oct. 1998, coll. Shirley Mohammed, stn.7B, W.43355 ; 1 specimen, Suva & Nadi Harbour, Benthic survey, Oct. 1998, coll. Shirley Mohammed, stn. 31A, W.43354 ; 9 specimens, Suva & Nadi Harbour, Benthic survey, Oct. 1998, coll. Shirley Mohammed, stn.34B, W.43357 .

Diagnosis. Prostomium rectangular or trapezium-shaped, with round or almost straight anterior margin, flattened dorsoventrally. 22–26 thoracic chaetigers; anterior segments without glandular pads. Branchial filament arising from chaetiger 3. All chaetae capillary of similar thickness. Thoracic chaetigers with 6–9 chaetae per ramus, abdominal chaetigers with 2–3 thin capillary chaetae in each ramus. Pygidium without cirri and other appendages.

Description. Body length of complete specimen (W.42862) about 4.5 mm, width 300 μm, consisting of 46 chaetigers. 22–26 thoracic chaetigers. Border between regions unclear, abdomen differs by position of parapodia on the middle of segment, less number of chaetae in bundles and longer segments ( Figs 9A View Figure 9 , 10A View Figure 10 , 11F View Figure 11 ). Anterior segments without glandular pads ( Fig. 9C View Figure 9 ).

Prostomium rectangular or trapezium-shaped, with round or almost straight anterior margin, flattened dorsoventrally ( Figs 9C,D View Figure 9 , 10C,D View Figure 10 , 11A,B View Figure 11 ). Prostomial furrow well defined, posterior ring wider than prostomium, shorter or same length with peristomium, with midventral notch ( Figs 9C,D View Figure 9 , 10C View Figure 10 , 11B View Figure 11 ). Branchial filament arising from anteromedial part of chaetiger 3 ( Figs 9C View Figure 9 , 10C View Figure 10 , 11B View Figure 11 ).

Chaetiger 1 with uniramous parapodia, all next segments with biramous parapodia with widely arranged rami. All chaetae hirsute capillaries; arranged in two rows. First chaetiger bearing 8–10 chaetae, next segments 6–9 chaetae in each ramus, neurochaetae in anterior rows slightly thicker than other chaetae ( Figs 10A,B,D View Figure 10 , 11B–E View Figure 11 ). Lateral organs seen behind chaetae fascicles beneath notopodia ( Fig. 11B View Figure 11 ). In abdominal region segments having two, rarely three thin, non-hirsute chaetae in each ramus ( Figs 10E View Figure 10 , 11F View Figure 11 ).

Pygidium without cirri and other appendages (probably lost) ( Fig. 10F View Figure 10 ).

Etymology. This species has been named in honour of Steven Keable, in recognition of his great effort to maintain and improve the collection of invertebrates of Australian museum.

Remarks. Few cossurid species also have the branchial filament on chaetiger 3 and no acicular chaetae in abdomen: Cossura candida Hartman, 1955 , C. bansei Hilbig , C. chilensis HartmannSchröder, 1965 , C. bansei Hilbig, 1996 , C. dayi Hartman, 1976 , C. delta Reish 1958 and C. consimilis Read, 2000 . Cossura keablei differs from them by the trapezium shape of prostomium and by having 2–3 capillary chaetae per ramus in the abdominal region. Moreover, C. chilensis has 19 thoracic chaetigers, C.delta has 15–18 thoracic chaetigers which is less, and C.consimilis has 27–31 thoracic chaetigers which is more than in C. keablei . Cossura brunnea Fauchald, 1972 has trapezium prostomium but differs by less number of thoracic chaetigers, dark pigment pattern over the median and posterior regions of its body, and having three long anal cirri.

References

Fauchald, K. 1972. Benthic polychaetous annelids from deep water off western Mexico and adjacent areas in the eastern Pacific Ocean. Allan Hancock Monographs in Marine Biology 7: 1 - 575.

Hartman, O. 1955. Endemism in the North Pacific Ocean, with emphasis on the distribution of marine annelids, and descriptions of new or little known species. In Essays in the Natural Sciences in Honor of Captain Allan Hancock on the Occasion of his Birthday, pp. 39 - 60. LosAngeles: University of Southern California Press.

Hartman, O. 1976 (1974). Polychaetous annelids of the Indian Ocean including an account of species collected by members of the International Indian Ocean Expeditions, 1963 - 64 and a catalogue and bibliography of the species from India. Journal of the Marine Biological Association of India 16 (1): 191 - 252.

Hartmann-Schroder, G. 1965. Zur Kenntnis des Sublitorals der chilenischen Kuste unter besonderer Berucksichtigung der Polychaeten und Ostracoden (Mit Bemerkungen uber den Einfluss sauerstoffarmer Stromungen auf die Besiedlung von marinen Sedimenten). Teil II. Die Polychaeten des Sublitorals. Mitteilungen aus dem Hamburgischen Zoologischen Museum und Institut 62 (Supl.): 159 - 305.

Hilbig, B. 1996. Family Cossuridae Day, 1963. In Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and Western Santa Barbara Channel. Vol. 6. The Annelida Part 3. Polychaeta: Orbiniidae to Cossuridae, ed. J. A. Blake, B. Hilbig, and P. H. Scott, pp. 385 - 402. Santa Barbara: Santa Barbara Museum of Natural History.

Read, G. B. 2000. Taxonomy and distribution of a new Cossura species (Annelida: Polychaeta: Cossuridae) from New Zealand. Proceedings of the Biological Society of Washington 113: 1096 - 1110.

Reish, D. J. 1958. Description of a new species of Cossura (Annelida: Polychaeta) from the Mississippi Delta. Journal of the Washington Academy of Sciences 48: 53 - 55.

Figures

Figure 9. Cossura keablei n. sp. W.45623, holotype, stereomicroscope. B–D stained with methylen blue. (A) general ventral view; (B) transitional region; (C) anterior end, dorsal view; (D) anterior end, ventrolateral view. Scale bars: A = 1 mm, B–D = 300 μm.

Figure 10. Cossura keablei n. sp. Compound microscope. (A) W.27171, paratype, general view, anterior end from lateral, then from dorsal; (B) W.46099, paratype, lateral view; (C) W.27175, anterior end, dorsal view; (D) W.27171, paratype, anterior end, lateral view; (E) W.27171, paratype, abdominal parapodia; (F) W.27171, paratype, posterior end, dorsolateral view. Scale bars: A, B = 500 μm, C, D = 200 μm, E, F = 100 μm.

Figure 11. Cossura keablein. sp. Paratype, W.42862, SEM.(A) general view; thorax and beginning of abdomen; anterior end:posterolateral view, abdomen: ventral view; (B) anterior end, lateral view (arrow indicates lateral organ); (C) notopodia of chaetiger 3; (D) neuropodia of chaetiger 4; (E) parapodia of chaetigers 18–20; (F) abdominal parapodia. Scale bars: A, B = 100 μm, C–F = 20 μm.