Lycopodina, LUNDBECK, 1905

Hestetun, Jon Thomassen, Tompkins-Macdonald, Gabrielle & Rapp, Hans Tore, 2017, A review of carnivorous sponges (Porifera: Cladorhizidae) from the Boreal North Atlantic and Arctic, Zoological Journal of the Linnean Society 181, pp. 1-69 : 37

GENUS LYCOPODINA LUNDBECK, 1905

Synonymy: Lycopodina Lundbeck, 1905: 58 , de Laubenfels, 1936: 122; Cotylina Lundbeck, 1905: 68 .

Diagnosis: Cladorhizidae pedunculate with body either in the form of an erect stem or sphere with filaments in all directions, or cup-shaped. Megascleres are mycalostyles and commonly shorter (tylo)styles. Microscleres are one type of arcuate or palmate anisochela where the smaller end is in the shape of a central plate and two rudimentary, flat, lateral teeth, all with serrated edges towards the middle. To this forceps spicules are often added, but may be rare or absent in particular species or specimens of a single species. Sigmas or sigmancistras are not present (from Hestetun et al., 2016b).

Type species: Esperella cupressiformis var. lycopodium Levinsen, 1887 (by subsequent designation de Laubenfels, 1936).

Remarks: Originally a subgenus of Asbestopluma erected by Lundbeck (1905) and raised to genus rank by de Laubenfels (1936), this genus was abandoned and more recently re-erected by Hestetun et al. (2016b) based on a combination of molecular and morphological results. It is the only cladorhizid genus that has forceps spicules. Sigmas or sigmancistras, present in all other cladorhizid genera, are absent.

The base spicule complement present in all Lycopodina species is megascleres such as styles, mycalostyles, subtylostyles, tylostyles or a combination, and palmate anisochelae. The morphology of the palmate anisochelae falls into two main categories, either similar to that of L. lycopodium ( Levinsen, 1887) , that is, clearly palmate with upper alae covering almost the whole shaft and a large, upper central tooth; or similar to L. infundibulum ( Levinsen, 1887) , that is arcuate to palmate, with the upper about half of the total length. In both cases, the lower end is modified into a characteristic set of a central raised and two lateral plates, each with one or several tips pointing upwards. This seems to be a further articulation of the similar structure common in the smaller anisochelae in Asbestopluma . Variations on this shape have been observed in a couple of species such as L. rastrichela ( Hestetun et al., 2015) .

The genus is challenging from a taxonomic perspective since several of the spicules associated with it are associated with reproductive structures and thus can be rare or absent in individual specimens. Conversely, published species descriptions may lack some of the spicules sometimes found in specimens of a particular species, and for many species in the genus, species descriptions only contain megascleres and anisochelae. Forceps spicules are associated with spermatic cysts ( Riesgo, Taylor & Leys, 2007) and are often rare or absent. Similarly, embryos can contain distinct spicules, typically a combination of smaller megascleres such as oxeas, strongyles and tylostyles not found in the rest of the sponge, but also anisochelae of a similar shape and slightly smaller size, than in the rest of the sponge (e.g. Lundbeck, 1905).

Finally, there are sometimes very subtle differences between certain species of the genus, and different species can have a more or less indistinguishable spicule complement, for example L. lycopodium , L. occidentalis ( Lambe, 1893) , L. novangliae sp. nov. and L. tendali sp. nov. described here are all quite similar. For several species, such as the four cup-shaped species described in this article, and L. cupressiformis ( Carter, 1874) and closely related species such as L. robusta ( Levinsen, 1887) and L. ruijsi ( van Soest, 2016) , it is possible that the current accepted species are not accurate. However, increasing the amount of molecular data on this group may pertly remedy this.