Genetic and morphologic identities of hydrozoans (Cnidaria, Hydrozoa) from reef patches of Santa Marta, Colombian Caribbean Author Torres-Rodríguez, Javier Tadeo Author Ortiz-Oyola, Daniel Universidad Jorge Tadeo Lozano. Department of Biological and Environmental Sciences. Cra. 2 # 11 - 68, El Rodadero, Santa Marta, Colombia Author Puentes-Sayo, Alejandra Universidad Jorge Tadeo Lozano. Department of Biological and Environmental Sciences. Cra. 2 # 11 - 68, El Rodadero, Santa Marta, Colombia Author Lecompte, Orlando P. Universidad Jorge Tadeo Lozano. Department of Biological and Environmental Sciences. Cra. 2 # 11 - 68, El Rodadero, Santa Marta, Colombia Author Jauregui, Aminta Universidad Jorge Tadeo Lozano. Department of Biological and Environmental Sciences. Cra. 2 # 11 - 68, El Rodadero, Santa Marta, Colombia text Zootaxa 2020 2020-03-27 4758 1 127 140 journal article 10.11646/zootaxa.4758.1.5 9c9e9e57-74b0-4d8e-869e-8382594b2f30 1175-5326 3731737 B3A6EB2D-0E5B-47F6-AB1D-799712B8B0F8 Halopteris alternata ( Nutting 1900 ) Fig. 2 Plumularia alternata Nutting, 1900: 62 , pl. 4, figs. 1, 2. Halopteris alternata Schuchert 1997: 42 , fig. 14. Type locality. Bahamas : Barracuda Rocks ( Nutting 1900: 62 ) . Voucher material. Reef patches of Santa Marta, Magdalena , Colombia . 53 feet ( 16 m ), October 2015 , SCUBA . Apical fragment of a colony 2 cm high, without hydrorhiza and with a male gonotheca. Description. Segmented obliquely monosiphonic hydrocaulus with alternating hydrocladium, each of the main segments of the hydrocaulus and hydrocladium presents a main hydrothecae and three or four nematothecas: two laterals, one inferior and one upper axillary to the hydrothecae present in the distal part of the colony. The intersegments have a nematotheca in the middle part. Each hydrocladium has lateral apophyses with a first short, square segment devoid of nematothecas, the second segment is elongated, and with a nematotheca in the middle zone, the rest of the hydrocladium has homomerous segmentation. As in the hydrocaulus, the intersegments have a nematotheca in the middle part. The hydrothecae has a cup shape, the adcauline and abcauline wall are straight laterally, and it joins the hydrocaulus from half to three quarters of the adcauline wall. The middle-lower nematotheca is immobile and the margin does not exceed the base of the hydrothecae, the lateral nematotheca is cone-shaped and emerges from a short and mobile pedicel, the margin is smooth and is not everted. The nematothecas of the intersegments are similar to the mid-lower, but are mobile and have a longer adcauline wall. The axillary nematotheca is the same as the rest of nematothecas. All the nematothecas present two cameras (bitalamic). The male gonotheca emerges from the hydrocaulus through a pedicel of a segment and presents an oblong shape. Reported distribution. The Gulf of Mexico ( Calder & Cairns 2009 ). Unites States in Florida ( Calder 2013 ). The Caribbean Sea ( Galea 2008 ; Calder & Kirkendale 2005 ). Eastern Atlantic ( Ansín Agís et al. 2001 ). Brazil ( Oliveira et al. 2016 ).