The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide

Abstract

The majority of Hydrozoa is represented by not readily noticeable, small species. In recent decades, however, taxonomic knowledge of the group has increased worldwide, with a significant number of investigations focused on the Mediterranean Sea. Over more than two decades, 115 species of hydrozoans were recorded from coastal waters along nearly 300 km of the Salento Peninsula (Apulia, Italy). For each species, records from different collections were merged into single sheets of a general database. For each species, the following information is reported: description, cnidome, biology, occurrence in Salento, worldwide distribution, and bibliography. Descriptions refer to the benthic hydroid stage and, when present, also to the planktonic medusa stage. The 115 species of Hydrozoa, recorded along the Salento coastline, represent 25% of the Mediterranean Hydrozoa fauna (totaling 461 species), and nearly 3% of 3,702 world's known species covered in a recent monograph. Four species are non-indigenous, three of them with invasive behavior (Clytia hummelincki, Clytia linearis, and Eudendrium carneum), and one species now very common (Eudendrium merulum) in Salento. The complete life cycle of Clytia paulensis (Vanhöffen, 1910) is described for the first time.

New Mediterranean Biodiversity Records 2019

“…Its distribution spread from tropical to sub-tropical waters of the Pacific, Indian and Atlantic Oceans (Chowdhury et al, 2016). For the Mediterranean Sea, the updated occurrence data of the species is reported in Figure 4 (Gravili et al, 2015;Furfaro et al, 2017;Saygin, 2017). Here we report a new Mediterranean record of P. porpita (Fig.…”

Effects of global warming on reproduction and potential dispersal of Mediterranean Cnidarians

“…Long time series are one of the clearer indicators of temperature shifts as a distribution driver in hydrozoans. In the Mediterranean Sea, over the last 50 years, the shallow water hydrozoan community displayed marked changes in species composition, bathymetric distribution, and reproductive timing, with increased dispersion and survival of species of warmwater affinity (including non-indigenous species) throughout the year (Bianchi & Morri 2003;Puce et al 2009;Gravili et al 2015aGravili et al , 2015bMartell et al 2017) (Figure 1a,b). In particular, Puce et al (2009) is the only study on hydroid communities in the Northern Mediterranean Sea demonstrating phenological changes linked to global warming across a 25-year period (from 1976 to 2004).…”

Additions to the hydroids (Cnidaria, Hydrozoa) of the Bay of Fundy, northeastern North America, with a checklist of species reported from the region

“…Meanwhile, each of the eight similar species listed above differs from H. praeparvum in various ways. For example, in H. pusillum, both pedicels and female gonothecae are strongly annulated, the aperture of the female gonotheca is lateral, and apical stolons are frequent (Gravili et al 2015). Halecium dichotomum stands apart in having long, slender pedicels and internodes, occasional dichotomous branching, hydrothecae that are less flaring, and female gonothecae that are prominently annulated, more slender, and possess a lateral aperture (Allman 1888;Millard 1975).…”