Pheronemoides, Li, 2017

Li, Xinzheng, 2017, A new genus and species of Pheronematidae (Porifera: Hexactinellida: Amphidiscosida) from the western Pacific Ocean, Zootaxa 4337 (1) : -

Pheronemoides , new genus

Type species. Pheronemoides fungosus gen. et sp. nov.

Diagnosis. Body shape of the sponge is spherical or hemispherical. The atrial areas and dermal areas are on opposite sides of the body. Basalia are gathered in a broad tuft that is positioned not exactly at the center of the body but rather in a basal crescent or amesially on the dermal surface. Marginalia located at the boundary between the atrial and dermal surfaces consist of diactins and sceptres. The choanosomal spicules are mainly pentactins and uncinates. The dermalia and atrialia are pinular pentactins and uncinates. The uncinates divided into three kinds: macrouncinates, mesouncinates and microuncinates. Prostalia basalia possess two-toothed anchors. Microscleres are usually amphidiscs and microuncinates, rarely microhexactins.

Etymology. Pheronemoides is named after Pheronema , a previously defined genus which the new genus most resembles.

Remarks. The new material is easily assignable to the family Pheronematidae Gray, 1870 in having a hemispherical or spherical body, bilateral symmetry, and two-toothed anchor basalia. However, we were not able to assign the specimen to any of the six known genera of pheronematids. Noting the positions of the basalia and marginalia, we infer that Pheronemoides gen. nov. is most similar to Pheronema and Sericolophus , and thus consider it intermediate between those two genera. Tabachnick (1999) considered Sericolophus as deriving from a hemispherical form of Pheronema . Viewed from above, Pheronemoides gen. nov. is hemispherical and bellshaped, with thin marginalia, which is consistent with the suppositions of Tabachnick (1999). In the new specimen, the basalia attach only in a semicircle on the dermal surface, thus leaving a large hollow between the dermal surface and basalia. We inferred the transitional stage of the new taxon from the basalia of the new specimen accordingly: (1) a broad tuft attached to the entire dermal surface on the bottom of the sponge in Pheronema , (2) a broad tuft attached to only a semicircular area on the dermal surface in Pheronemoides gen. nov., and (3) a compact tuft at the center on the bottom in Sericolophus . The location of prostalia also indicates a transitional stage: (1) marginalia are located on the dermal surface in most species of Pheronema , (2) marginalia are located at the boundary between the dermal and atrial surfaces in Pheronemoides gen. nov., and (3) marginalia are located on the atrial units in Sericolophus . Therefore, considering the body shape of the sponge together with the location of the basalia and the marginalia, we describe the new species as belonging to a previously undescribed genus that is transitional between Pheronema and Sericolophus . Poliopogon and Pheronemoides gen. nov. are alike in external shape. Most species of Poliopogon are columnar and their dermal and atrial surfaces are located on the left and right side of the body with concave atrial cavities. But the dermal and atrial surfaces of our new genus are located on the upper and lower side of the body with concave dermal cavity.