Biodiversity assessment in the Lower Mekong basin: First record of the genus Oncosclera (Porifera: Spongillina: Potamolepidae) from the Oriental Region

Abstract

Taxonomic richness of Thai Spongillina numbers so far seven species (five genera, one family). The first record of the genusOncosclera Volkmer-Ribeiro, 1970 belonging to the family Potamolepidae Brien, 1967 is here reported with the description ofa new species from the Pong River (NE Thailand, Oriental Region) in the framework of a biodiversity assessment in the LowerMekong Basin. An emended diagnosis of the genus is also provided. The new species, ascribed to the genus Oncosclera fordiagnostic traits of the skeleton and the gemmular architecture, differs from all the other known species of the genus in itsunique combination of diagnostic traits. O. asiatica sp. nov. is characterised by i) more or less alveolate skeleton, ii) conulosesurface with a network of branched subdermal canals, iii) acanthoxeas as dominant megascleres and less frequentacanthostrongyles, iv) gemmular theca sublaminar of compact spongin with a scantly developed pneumatic layer of fibrousspongin, and v) gemmuloscleres as acanthostrongyles from elongated to ovoid with tubercles/spines particularly dense towardsthe tips. Despite the extremely disjunct distribution O. asiatica is morphologically similar to O. intermedia and O. jewelli fromthe Neotropical Region and O. gilsoni from Pacific Islands, from which the former diverges for megascleres and/or gemmuloscleres traits.

Minimalist barcodes for sponges: a case study classifying African freshwater Spongillida

“…In combination with results from earlier (although not yet holotype-verified) molecular analyses (e.g. Meixner et al 2007, Itskovich et al 2013b Neotropical, Australian, Oriental and Nearctic distribution (Manconi and Pronzato 2002, Manconi et al 2012, Copeland et al 2015.. Our present study comprises sequences of all Afrotropical genera (Echinospongilla Manconi & Pronzato, 2002, Oncosclera Volkmer-Ribeiro, 1970, Potamolepis Marshall, 1883, Potamophloios Brien, 1970. The taxa fall into two distinct clades (Fig.…”

A First Account of Freshwater Potamolepid Sponges (Demospongiae, Spongillina, Potamolepidae) from the Middle Eocene: Biogeographic and Paleoclimatic Implications

“…For example, C. mesopotamica and C. thysii can have similar megascleres and gemmuloscleres but these species also produce oxea megasclere and microsclere spicules that were not observed in the Giraffe samples containing numerous gemmular strongyles. The species Corvospongilla siamensis Manconi and Ruengsawang (Ruengsawang et al, 2012) described from Thailand has gemmuoscleres of similar morphology but they are adorned with spines and never have inflated ends. This species is also characterized by micropseudobirotule microscleres.…”

“…At present, representatives of the Potamolepidae occur only in Africa (four genera), the Neotropics (three genera), the Pacific Oceanic Islands (one genus) (Manconi and Pronzato, 2002), and Indochina (one genus) (Manconi et al, 2012). The family is thus strongly restricted to tropical climate regimes, with no known temperate, boreal, or polar occurrences (Manconi andPronzato, 2002, 2009).…”

“…As is true of most freshwater sponges, living potamolepid sponges are characteristic of lakes and rivers and require firm substrates, such as rocks, wood fragments or plants, for colonization (Frost et al, 2001;Manconi andPronzato, 2002, 2009). Pinheiro (2007) reported that the potamolepid genera Oncosclera, Sterrastolepis and Uruguaya from Brazil required hard substrata, typically rock or concrete, and some Onclosclera species may grow on bamboo sticks (Manconi et al, 2012). One species, Oncosclera spinifera, inhabits very shallow (,20 cm deep) water with temperature 308C and pH¼7.…”

Trends and Gaps in Scientific Production on Freshwater Sponges

“…In relation to the discovery of new species, new records continue to occur in other parts of the world, as in the United States of America (Peterson & Addis 2000, Annesley et al 2008, Copeland et al 2015; in Southeast Asia (Lim & Tan 2013, Manconi et al 2012 and in the African continent , in Venezuela (Quintero et al 2017) and in Northeast Australasia (Ruengsawang et al 2017). Despite these records, continental sponges are poorly explored in these parts of the planet, evidencing a gap to this area of knowledge.…”