Xenocoeloma alleni ( Brumpt, 1897 )

Boxshall, Geoff A., O’Reilly, Myles, Sikorski, Andrey & Summerfield, Rebecca, 2019, Mesoparasitic copepods (Copepoda: Cyclopoida) associated with polychaete worms in European seas, Zootaxa 4579 (1), pp. 1-69 : 61-62

Xenocoeloma alleni ( Brumpt, 1897)

Syn: Saccopsis alleni Brumpt, 1897

Scandinavian material examined: 1♀ from Polycirrus medusa Grube, 1850 , Huldra, Stn 1-1 (60.85328°N, 02.650849°E), depth 123 m, 4 June 1999; collected by A. Sikorski. 1♀ from P. medusa, Balder 2000 , Stn 10-4 (59.17966°N, 02.414501°E), depth unknown, 31 May 2000; collected by A. Sikorski. 1♀ from P. medusa, Prosj 2302 , Smeerenburgfjord 4, Stn 04-5 (79.74367°N, 11.11°E), depth 203 m, 14 May 2003; collected by A. Sikorski. 1♀ from P. medusa, Hydro 2003 , Stn 1-5 (72.55416°N, 20.98141°E), depth 393 m, 13 June 2003; collected by A. Sikorski. 1♀ from P. medusa, Hydro 2003 , Stn 2-3 (72.53105°N, 21.05106°E), depth 372 m, 14 June 2003; collected by A. Sikorski. 1♀ from P. medusa, Veslefrikk, Stn 10-1 (60.7857°N, 02.89033°E), depth 171 m, 23 May 2004; collected by A. Sikorski. 1♀ from P. medusa, Oseberg Øst, Stn 18-1 (60.7127°N, 02.9082°E), depth 152 m, 25 May 2004; collected by A. Sikorski. 1♀ from P. medusa, Sandnessjøen 2007 , Stn Lå3-B (66.23202°N, 12.35218°E), depth 38 m, 0 3 January 2007; collected by A. Sikorski. 2♀♀ from 2 specimens of P. medusa, Sandnessjøen 2007 , Stn Lå2-B (66.23468°N, 12.33743°E), depth 45 m, 0 3 January 2007; collected by A. Sikorski. 1♀ juvenile attached laterally on mid-body of Polycirrus latidens, Sandnessjøen 2007 , Stn Lå3-B (66.23202°N, 12.35218°E), depth 38 m, 0 3 January 2007; collected by A. Sikorski. 3♀♀ from Polycirrus norvegicus Wollebaek, 1912 , Statfjord A 2005, Stn 4-3 (61.24075°N, 01.887778°E), depth 146 m, 15 June 2005; collected by A. Sikorski. 1♀ from P. norvegicus, Codfarmers, Mørkvedbukta Stn DYP2-1 (67° 16.528’N, 14° 33.207’E), depth 56 m, 15 July 2009; collected by A. Sikorski. 1 non-ovigerous ♀ from Polycirrus plumosus (Wollebaek, 1912) , 8132 Hestholmen C, Stn Hest 3-2 (67.15099°N, 14.03847°E), depth 276 m, 0 5 February 2016; collected by A. Sikorski. 1 nonovigerous ♀ from P. plumosus , 8132 Hestholmen C, Stn Hest 1-2 (67.14753°N, 14.02007°E), depth 143 m, 0 5 February 2016; collected by A. Sikorski. 1♀ from Polycirrus sp., Balder, Stn 16-3 (59.1757°N, 02.3778°E), depth 125 m, 26 May 1997; collected by A. Sikorski. 1♀ from Polycirrus sp., Balder, Stn 31-5 (59.1877°N, 2.435°E), depth 125 m, 27 May 1997; collected by A. Sikorski. 1 ovigerous ♀ and 1 developing immature ♀ from Amaeana trilobata (M. Sars, 1863) , Vigdis PT 2, Stn 11-5 (61.37356°N, 02.115149°E), depth 281 m, 12 June 2005; collected by A. Sikorski; NHMUK Reg. No. 2017.478.

British material examined: 1 ovigerous ♀ detached from host ( Polycirrus plumosus ) but ovisac entangled in host tentacles, Dove Marine Lab., Stn M1 (=Stn 26), depth 48 m, collected by P.R.Garwood, 0 8 March 1994 (see O’Reilly & Geddes, 2000). 1 ovigerous ♀ on Polycirrus sp. ( medusa ?), north Irish Sea, Block 109, Stn 12 (53° 54’ 51.3”N, 04° 15’ 58.7”W) depth 44 m, collected by Sue Hamilton, September 1995. 2 ♀♀ on single Polycirrus medusa , north Irish Sea, Block 112, Stn unknown, collected by Sue Hamilton, September probably 1995. 1 ♀ from Polycirrus plumosus , Northumberland, Dove Marine Lab., Stn M1 (= Stn 26), depth 48 m, collected by P.R.Garwood, 0 4 September 1996 (see O’Reilly & Geddes, 2000). 1 ovigerous ♀ on Polycirrus norvegicus (Unico sample 18383), Liverpool Bay, CEFAS Stn M10 (53° 31’N, 03° 31’W), collected 0 5 September 1996. 1 ovigerous ♀, 1 mature ♀ on Polycirrus sp. (Unico sample 21664), Liverpool Bay, ERM Day Grab 49a (53° 32.196’N, 03° 29.995’W), collected 30 July 2001. 1 ovigerous ♀, detached (with Polycirrus norvegicus ). (Unico sample 25309), Liverpool Bay, Day Grab M 10x 13 d (53.4408°N, 03.8207°W), collected August 2001. 1 immature ♀ attached to oral area of P. norvegicus, Unico 37927, English Channel, CEFAS, Stn EC 5, sample 232a, (50.50015°N, 01.99826°W), collected September 2005. 1 immature ♀ attached to abdomen of Polycirrus sp?, Unico. 37932, English Channel, CEFAS, Stn EC 29, sample 236c, (50.30227°N, 01.96289°W), collected September 2005. 1 ovigerous ♀ on frontal cushion of Polycirrus sp., (Unico 41477), Irish Sea, CEFAS Stn ISB55c (54° 00’N, 04° 00’W), depth unknown. 1 mature ♀ on dorsal cushion of Polycirrus ? norvegicus , (Unico 44294), CEFAS, Tyne, Stn NT6c, collected 2007. 2 mature ♀ on Polycirrus sp. (Unico 47765), survey EHS WFD, Down Coast, South Rock, Stn SRK-b (54.41908°N, 05.39333°W) depth 24 m,collected 0 9 July 2010 by Tim Mackie. 2 mature ♀ on lip of P. plumosus , North Kishorn, Stn. 161mW, collected by Sue Hamilton, April 2012. 1 immature ♀ on P. plumosus , NW Hutton Field, BPx054, 7.5km N (61.1643°N, 01.3091°E) depth 145 m, collected by P.R. Garwood, 2015? 1 ovigerous ♀ on Polycirrus sp. fragment, North Norfolk, Cromer Shoals MCZ, (APEM) Stn 169, CSC B040 (52° 57.066’N, 01° 29.388’E), depth 19 m, 12 September 2014. 1 mature ♀ on Polycirrus sp., Shetland, Bow of Hascosay, SEPA Stn 200mW (60.61181°N, 01.0108560°W.), depth 13 m, collected 0 2 June 2017. NHMUK Reg. Nos 2018.173-182.

Descriptions. Six ovigerous females from Polycirrus medusa caught in Scandinavian waters were measured: mean ectosoma length was 1.92 mm (range 0.88 to 2.73 mm), mean maximum width of ectosoma was 0.74 mm (range 0.44 to 1.10 mm); mean L:W ratio 2.31:1 (range 1.79 to 3.10:1). The egg sacs are multiseriate, slightly curved and up to 4.5 mm long for largest adult female (2.73 mm ectosoma length). The ectosoma of an ovigerous female from P. medusa in the northern Irish Sea measured 1.27 by 0.69 mm, a L:W ratio of 1.83:1, and two nonovigerous but mature females from the same host and geographical area had L:W ratios of 2.0:1 and 2.17:1.

The material from Polycirrus norvegicus included 2 ovigerous adult females ( Fig. 27B ) emerging from the head of the host. Each has a cylindrical ectosoma: ectosoma lengths were 1.28 and 1.36 mm, and widths 0.56 and 0.70 mm, respectively, giving L:W ratios of 1.94:1 to 2.29:1. The egg sacs are multiseriate, slightly curved and about 1.1 to 1.2 mm long.

The Scandinavian material from Polycirrus plumosus comprised 2 non-ovigerous adult females each emerging from the head of its host. Each has a cylindrical ectosoma: ectosoma lengths were 1.69 and 2.38 mm by 0.73 and 0.77 mm wide, respectively, giving a L:W ratio of 2.32:1 to 3.09:1. Ovigerous females from P. plumosus caught in the North Sea off Northumberland measured 2.39 by 0.81 mm, a L:W ratio of 2.95:1, and 4.04 by 1.19 mm, a L:W ratio of 3.39:1.

Ovigerous females from unidentified Polycirrus sp. collected in British waters exhibited a length range of 1.04 to 1.96 mm and a width range of 0.42 to 0.96 mm. The range of L:W ratios was 1.80:1 to 2.82:1.

The ovigerous adult female from Amaeana trilobata has a stout cylindrical ectosoma ( Fig. 27A ) about 1.47 mm long by 0.84 mm wide, giving an L:W ratio of about 1.75:1. It is attached at its anterior end and the common genital pore lies in the middle of its posterior surface. Both paired egg sacs originate from the common pore. The egg sacs are multiseriate, slightly curved and about 1.95 mm long; each egg sac becomes slightly wider posteriorly. The immature female from the same host has a cylindrical ectosoma 0.67 mm long by 0.34 mm wide (L:W ratio 1.97:1). It lacks any trace of a posterior genital pore.

Remarks. This material is all tentatively attributed to X. alleni solely on the basis of the L:W ratio of the ectosoma of ovigerous females. The material from P. medusa exhibits ratios varying from 1.79:1 up to 3.10:1, and this range encompasses the variation shown by material from all the other hosts except the ovigerous female from Amaeana trilobata , which was 1.75:1. One female from Polycirrus plumosus caught in the North Sea, off the coast of Northumberland was recorded by O’Reilly & Geddes (2000) as X. alleni . This specimen had the highest value for the L:W ratio, 3.39:1. This value falls outside the range of 1.79 to 3.10:1, which we found was typical for X. alleni . None of the specimens attains a L:W ratio approaching the 4.0–4.8:1 given for X. brumpti . However, with so few morphological features, all these identifications should be regarded as in need of validation once molecular diagnostics become available.

Figures

FIGURE 27. Xenocoeloma alleni (Brumpt, 1897). A, ectosoma of ovigerous female from Amaeana trilobata; B, ectosoma of ovigerous female from Polycirrus norvegicus caught in Norwegian waters. Xenocoeloma brumpti Caullery & Mesnil, 1915. C. ectosoma of ovigerous female from Polycirrus norvegicus caught in Liverpool Bay. Xenocoeloma orbicularis sp. nov. ovigerous female holotype. D, ectosoma, dorsal view showing paired eggs sacs emerging from common pore; E, same, lateral. Aphanodomus terebellae (Levinsen, 1878) adult female, F, habitus with 1 multiseriate and 1 spent egg sac. Scale bars: A, B, C, F, 1.0 mm; D, E, 0.5 mm.