Plakortis clarionensis, Cruz-Barraza & Vega & Carballo, 2014

Cruz-Barraza, José Antonio, Vega, Cristina & Carballo, José Luis, 2014, Taxonomy of family Plakinidae (Porifera: Homoscleromorpha) from eastern Pacific coral reefs, through morphology and cox 1 and cob mtDNA data, Zoological Journal of the Linnean Society 171 (2), pp. 254-276 : 265-266

publication ID	https://doi.org/ 10.1111/zoj.12137
persistent identifier	https://treatment.plazi.org/id/4617186B-FFA8-FF98-FF34-EDC5FC17392A
treatment provided by	Marcus
scientific name	Plakortis clarionensis
status	sp. nov.

Treatment

PLAKORTIS CLARIONENSIS View in CoL SP. NOV.

( FIGS 2D View Figure 2 , 5 View Figure 5 )

Material examined

Holotype: MNCN 1.01 About MNCN /696 Roca Norte , Clarión Island (Revillagigedo), 18°47′14″N, 110°55′42″W, 4 m depth, 12.iii.2005 GoogleMaps . Paratypes: LEB-ICML-UNAM-1240, Roca Norte , Clarion Island (Revillagigedo), 18°47′14″N, 110°55′42″W, 4 m depth, 12.iii.2005 GoogleMaps . LEB-ICML-UNAM- 1253, Pináculo Norte (Revillagigedo), 18°51′4″N, 110°59′53″W, 4 m depth, 12.iii.2005 GoogleMaps .

ZooBank LSID: urn:lsid:zoobank.org:act:734EED7F-8AA6-4899-B3C3-1DE7346178A3 .

Etymology

The epithet refers to the type locality Clarion Island (Revillagigedo archipelago) where the specimens of this species were collected.

Diagnosis

Dark brown (in preserved condition), encrusting to cushion-shaped sponge, with smooth surface. Consistency is cartilaginous-like, but inside is fleshy. Spicules are diods and triods, which are included in a dense collagen layer, without alveolar skeletal specialization.

Description

Encrusting to cushion-shaped sponge from 0.2 to 1.5 cm in thickness, spreading between coral branches and over rocks ( Fig. 2D View Figure 2 ). The specimens cover areas up to 10 × 8 cm. Surface is uneven and rugose, with rounded bumps, which gives a granular appearance. Sponge borders in contact with the coral structures become irregular, taking the substrate’s form. Between the bumps there are small ostial pores of 330–670 μm in diameter. The surface also presents very small subectosomic canals 150–250 μm in diameter. Only one circular-shaped oscule was found, of 1 mm in diameter. The consistency of the surface is slightly cartilaginous, but the interior is fleshy. Colour in life was not observed; in spirit it is dark and light brown on the surface and the choanosome is pale yellow.

Spicules: diods and triods ( Table 4). Diods are thin and elongated, typically curved in the centre, with one, two or more well-marked bent. The ends are straight with sharp or slightly rounded tips ( Fig. 5A View Figure 5 ). Diods are abundant; they measure 17.5–77.5 μm long and 1.25– 3 μm wide. Triods usually present equal angles, but can be uneven with ‘T’ or ‘Y’ shape ( Fig. 5B View Figure 5 ). Sizes of the rays are variable, 10–30 μm long (total spicule length 20–62 μm).

Skeleton: the skeletal structure is formed by diods in abundance and some triods, which are included in a dense collagen layer, without alveolar or skeletal specialization and no apparent organization. The ectosome is a nondetachable pigmented layer (up to 1 mm in thickness), with dispersed diods ( Fig. 5C View Figure 5 ), and very well differentiated from the choanosome ( Fig. 5D View Figure 5 ). In the subectosomal area an agglomeration of spicules and pigments is present; this layer is also characterized by the presence of several canals, rather than the deep choanosome.

Ecology and distribution

Specimens were collected in two localities from Revillagigedo archipelago: Clarion Island and Pináculo Norte ( Fig. 1 View Figure 1 ). Specimens were found on pocilloporid coral branches and over rocks at 4 m depth.

Remarks

Currently, there are three species of Plakortis from the East Pacific coast: Plakortis albicans (see below for remarks on this species) and Plakortis simplex ( Austin, 1996) from Mexico, and Plakortis galapagensis from the Galapagos Islands.

The species Plakortis simplex was originally described in the Mediterranean Sea ( Schulze, 1880) and later cited around the world. However, recent authors have discussed the conspecificity of different populations, suggesting a species complex (sibling species). Therefore, the Mexican record by Austin (1996) is probably a different species. However, a more detailed description of this material would be necessary to confirm its taxonomic status.

The geographically closest species to Plakortis clarionensis sp. nov. is Plakortis galapagensis , which is different to the new species in external and internal characteristics. Plakortis galapagensis is an encrusting (5 mm thick), beige-coloured species whereas Plakortis clarionensis sp. nov. is more cushion- shaped (up to 1.5 cm thickness), dark brown sponge. Plakortis galapagensis presents an alveolar skeletal structure whereas Plakortis clarionensis sp. nov. has a dense collagen layer, without skeletal specialization. The spicules also vary in size; diods are larger and in two size categories in Plakortis galapagensis (126–165 by 4–8 μm and 27–92 by 1.5–4 μm) than in Plakortis clarionensis sp. nov., which only presents one, smaller size category (17.5–77.5 by 1.3–3 μm).

The species Plakortis nigra Lévi, 1953 , from the Red Sea and Plakortis insularis Moraes & Muricy, 2003 , from north-east Brazil are the only two species possessing small diods. The rest of the known species have diods bigger than 100 μm long (see Table 4). Plakortis nigra differs from Plakortis clarionensis sp. nov. in the black colour, porous surface, and because its skeletal structure is formed only by diods. Plakortis insularis is encrusting, massive, rounded or flat in shape, and dark to light brown in colour. The skeleton is very similar to P. clarionensis sp. nov., with diods and triods in low density forming a confuse structure. However, P. insularis has larger diods, which always end in a sharp tip, whereas the diods in Plakortis clarionensis sp. nov. are smaller and end in a sharp or rounded tip. Plakortis insularis produces a dark brown substance when preserved, which was not observed in our specimens of Plakortis clarionensis sp. nov. The consistency of P. insularis is soft, compressible, and fragile, whereas in Plakortis clarionensis sp. nov. it is elastic and resistant at the surface, although the interior is fleshy.