Plakortis albicans, Cruz-Barraza & Vega & Carballo, 2014, 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 : 266-269

PLAKORTIS ALBICANS CRUZ- BARRAZA & CARBALLO, 2005 ( FIGS 2E , 6 )

Synonymy

Plakortis albicans Cruz-Barraza & Carballo, 2005: 4 .

Material examined

LEB-ICML-UNAM-1106, Punta Mita (Nayarit), 20°46′20″N, 105°32′49″W, 3 m depth, 19.ii.2005 . LEB- ICML-UNAM-1283, El Arrocito (Oaxaca) 15°44′25″N, 96°51′31″W, 4 m depth, 11.iv.2005 . LEB-ICML-UNAM- 1408, San Agustín (Oaxaca) 15°41′9″N, 96°13′46″W, 6 m depth, 9.iv.2005 . LEB-ICML-UNAM-1718, Bahía Tiburones, Isabel Island (Nayarit), 21°50′38″N, 105°52′14″W, 2 m depth, 29.iii.2011 . LEB-ICML-UNAM- 2009, Caleta de Bines, Socorro Island (Revillagigedo), 18°44′10″N, 110°57′37″W, 6 m depth, 7.xi.2009 . LEB- ICML-UNAM-2070, Punta Mita (Nayarit), 20°46′20″N, 105°32′49″W, 3 m depth, 29.iii.2012 . LEB-ICML-UNAM- 2071, Bahía Tiburones, Isabel Island (Nayarit), 21°50′38″N, 105°52′14″W, 2 m depth, 26.iii.2012 . LEB- ICML-UNAM-2356, Bahía Tiburones, Isabel Island (Nayarit), 21°50′38″N, 105°52′14″W, 2 m depth, 29.xi.2012 . LEB-ICML-UNAM-2357, Bahía Tiburones, Isabel Island (Nayarit), 21°50′38″N, 105°52′14″W, 2 m depth, 5.ix.2011 . LEB-ICML-UNAM-2358, Bahía Tiburones, Isabel Island (Nayarit), 21°50′38″N, 105°52′14″W, 2 m depth, 5.ix.2011 .

Description

Thickly encrusting species (from 1 to 2 mm in thickness), from 1 to 4 cm diameter, meandering between dead coral base and rocks ( Fig. 2E ). The surface is smooth, characteristically sculpted by subectosomal canals (50– 150 μm in diameter). It also has subectosomal spaces, which are regularly distributed over the surface (from 33.3 to 83 μm in diameter). Oscula are circular-shaped and slightly elevated from the surface, measuring 0.5 mm in diameter. Consistency is slightly compressible but firm, easy to tear. Colour in life is white to ivory and dark greyish-blue, preserved it turns paler.

Spicules: diods and triods ( Table 4). Diods are irregularly curved along the shaft, sometimes bent one or two times near the centre ( Fig. 6A ). They are abundant and variable in size, from 12.5 to 162.5 μm long by 0.3 to 5 μm width. The triods are less abundant than diods, with an irregular or equal-angled shaped. The rays are mostly straight or slightly bent. The size of the rays is very variable, 5–37.5 μm long, (total spicule length 10–72.5 μm).

Skeleton: ectosome possesses a tangential alveolar skeletal structure of spicule tracts (5 to 15 μm in diameter), with meshes from 15 to 50 μm in diameter ( Fig. 6B ). The choanosomal skeleton is a dense and relatively disorganized reticulation of spicule tracts, with meshes from 20 to 50 μm in diameter ( Fig. 6C ). Choanosomal canals from 70 to 350 μm in diameter.

DNA barcode sequence data

Two specimens from Isabel Island, (Nayarit) and two from the type locality, Mazatlan Bay ( Cruz-Barraza & Carballo, 2005), were sequenced and 584 bp of cox1 and 388 bp cob mtDNA were used for comparison. Individuals showed an identical sequence for both fragments, confirming together with morphology that they correspond to the same species. Comparison of our sequences with sequences available in GenBank showed that the nearest species to Plakortis albicans is Plakinastrella sp. from Florida, USA (EU237487.1 named as Plakinastrella cf. onkodes ) with 99% similarity for cox1 and 98% for cob. Although the specimen of this sequence appears in GenBank as Plakinastrella cf. onkodes , it was originally identified as Plakortis angulospiculatus ( Carter, 1882) (by Lavrov et al., 2008), and in later revisions it was named as Plakinastrella sp. (by Gazave et al., 2010) and Plakinastrella onkodes (by Ereskovsky et al., 2014).

Sequences of cox1 and cob of Plakortis albicans have been deposited in GenBank with accession numbers: cox1 pending; cob: pending.

Ecology and distribution

The species has been described from Lobos Island in Mazatlan Bay (Sinaloa, Mexico, East Pacific Ocean ). In the present study, specimens were collected in shallow water (3 to 6 m depth) over dead corals from Bahía Tiburones ( Isabel Island , Nayarit), Punta Mita (Nayarit), Caleta de Bines (Socorro Island, Revillagigedo), El Arrocito and San Agustín (Oaxaca). This is the first record for Plakortis albicans associated with coral reefs from the Mexican Pacific coast .

Remarks

Specimens described here as Plakortis albicans agree very well with the morphological description of the species ( Cruz-Barraza & Carballo, 2005), and sequences also show a nucleotide composition identical to the specimens collected from the type locality, Mazatlán Bay.

Figures

Figure 2. External morphologies of plakinid species from the eastern Pacific. A, B, Plakina muricyae sp. nov. C, i, Plakina paradilopha sp. nov.; ii, Plakina muricyae sp. nov. D, Plakortis clarionensis sp. nov. E, Plakortis albicans Cruz-Barraza & Carballo, 2005. F, Plakinastrella clippertonensis van Soest et al., 2011.

Figure 6. Scanning electron microscopy images of spicules and skeletal structure of Plakortis albicans Cruz-Barraza & Carballo, 2005. A, diods and triods. B, tangential view of ectosomal alveolar skeleton. C, transversal view of the choanosome.