Nemertesia irregularis ( Quelch, 1885 )

Gil, Marta & Ramil, Fran, 2025, Hydroids (Cnidaria, Hydrozoa) from Guinea Bissau, Zootaxa 5577 (1), pp. 1-89 : 66-67

Nemertesia irregularis ( Quelch, 1885)

( Fig. 11D–E )

Antennularia irregularis : Gil et al., 2020: 446–452, figs 9, 10, 11 (synonymy).

Material examined. BISSAU-0810, stn BS132, 11º31'33"N, 17º14'07"W, depth unknown, 23-X-2008: four colonies

(one with gonothecae), 36–54 mm high, of which one growing on Diphasia margareta and another one on a worm tube.

BISSAU-0810, stn BS147, 11º08'35"– 11º08'27"N, 17º11'31"– 17º10'37"W, 186–306 m, 26-X-2008: one colony without gonothecae, substrate unknown.

BISSAU-0810, stn BS151, 11º05'09"– 11º04'15"N, 17º03'15"– 17º03'10"W, 46–47 m, 26-X-2008: one colony with gonothecae, 104 mm high, substrate unknown.

BISSAU-0810, stn BS152, 10º31'12"– 10º30'19"N, 17º12'34"– 17º12'32"W, 300–305 m, 27-X-2008: 43 colonies (five with gonothecae), 26–128 mm high, of which two growing on Lytocarpia myriophyllum .

BISSAU-0810, stn BS172, 10º07'45"– 10º07'02"N, 16º34'11"– 16º33'37"W, 223–224 m, 31-X-2008: two colonies without gonothecae, growing on Lytocarpia myriophyllum .

BISSAU-0810, stn BS182, 10º14'14"– 10º13'22"N, 16º32'49"– 16º32'44"W, 211–224 m, 1-XI-2008: one colony without gonothecae, 64 mm high, growing on Lytocarpia myriophyllum .

BISSAU-0810, stn BS199, 10º16'49"– 10º17'29"N, 16º22'15"– 16º22'49"W, 65–70 m, 4-XI-2008: one colony without gonothecae, 42 mm high, substrate unknown.

BISSAU-0810, stn BS200, 10º18'55"N, 16º25'07"W, 79 m, 4-XI-2008: one colony with gonothecae, 358 mm high, substrate unknown.

Remarks. For many years, this species has been considered as a junior synonym of Nemertesia antennina ( Linnaeus, 1758) but, after reviewing a large number of specimens from Northwest Africa, Gil et al. (2020) emphasized the distinguishing characters allowing their specific separation.

The material studied here agrees with that described by Gil et al. (2020) and, based on their records, we have extended its geographical distribution southwards. In addition, gonothecae were found for the first time in October.

Most of the colonies of N. irregualis studied herein were used as substrates by other hydroids. In some colonies from station BS152, we observed a phenomenon of auto-epizoism.

Biology. Some colonies of N. irregularis have been found growing on D. pertusum ( Gil et al. 2020) . In the northern hemisphere, fertile material has been found in May, June ( Ramil & Vervoort 1992a; Ansín Agís et al. 2001, both as N. antennina ) November and December ( Gil et al. 2020).

In our material, some colonies were found growing on D. margareta , L. myriophyllum and a worm tube. Gonothecae were found in October and November.

Distribution. Nemertesia irregularis is an East Atlantic species ( Gil et al. 2020) with a wide bathymetric distribution, ranging from 12 to 2450 m depths ( Ansín Agís et al. 2001). In West Africa, it was recorded from Morocco to the Cape Verde Islands ( Gil et al. 2020).

Our material was collected at depths between 46–306 m.

Figures

FIGURE 11.A. Polyplumaria flabellata G.O. Sars, 1874(stnBS133), portion of colony with a hydrocladium.B. Pseudoplumaria marocana (Billard, 1930) (stn BS143), portion of hydrocladium. C. Kirchenpaueria pinnata (Linnaeus, 1758) (stn BS147), portion of hydrocladium. D–E. Nemertesia irregularis (stn BS132); portion of hydrocladium (D); female gonotheca (E). F. Nemertesia ventriculiformis (Marktanner-Turneretscher, 1890) (stn BS152), portion of hydrocladium. Scales: a–f, 0.5 mm.