Cherokeesia armata, Copeland, John, Pronzato, Roberto & Manconi, Renata, 2015

Copeland, John, Pronzato, Roberto & Manconi, Renata, 2015, Discovery of living Potamolepidae (Porifera: Spongillina) from Nearctic freshwater with description of a new genus, Zootaxa 3957 (1), pp. 37-48 : 40-44

Cherokeesia armata n. sp.

[Type species] ( Figs 1 –4; Tabs 1–2; Appendix 1)

Holotype. USNM 1264992, type locality Nolichucky River (36°09′22′′ N, 82°43′27.5′′ W) an eastern headwater tributary of the Tennessee River, USA, Tennessee, Blue Ridge Province, J. Copeland leg., 2, July 2014. Paratypes. USNM 1264993–1265000, Nolichucky River (36°09′22′′ N, 82°43′27.5′′ W) an eastern headwater tributary of the Tennessee River, USA, Tennessee, Blue Ridge Province, J. Copeland leg., 2, July 2014; USNM 1266150, Nolichucky River (36° 09′ 22′′ N, 82° 43′ 27.5′′ W) an eastern headwater tributary of the Tennessee River, USA, Blue Ridge Province, J. Copeland leg. 26 June 2013 on 1 slide; USNM 1266148, ibid., on 2 slides; USNM 1266151, ibid., on 2 slides; USNM 1266149, Nolichucky River (36° 10′ 54.1′′ N, 82° 31′ 45.4′′ W) an eastern headwater tributary of the Tennessee River, USA, Tennessee, Blue Ridge Province, J. Copeland leg., 29 July 2013 on 1 slide; USNM 1266145, Hiwassee River (35° 13′ 13.6′′ N, 84° 31′ 07.1′′ W), an eastern headwater tributary of the Tennessee River, USA, Tennessee, Blue Ridge Province, J. Copeland leg., 26 July 2013 on 2 slides; USNM 1266146, ibid., on 2 slides; USNM 1266147, ibid., on 2 slides. DTRG FW 763 specimen fragment is from Nolichucky River (36° 10′ 54.1′′ N, 82° 31′ 45.4′′ W) collected 29 July 2013 ( Fig. 1 ).

Comparative material. Echinospongilla brichardi (Brien, 1974) holotype MRAC 1430, leg. M. Brichard, v.1973, Urundi, Lake Tanganyika, Usumbura. Potamolepis stendelli Jaffe, 1916 holotype MRAC 410-411, Kasenga, Lake Luapula, on shell fragments, mission Stappers, 25.vii.1911, 0–10 m depth, by dredge. Oncosclera jewelli (Volkmer, 1963) holotype MNRJ 0 0 1, Rio Thainas, São Francisco da Paula, Rio Grande do Sul, 10.ix.1960, det. C. Volkmer-Ribeiro. Oncosclera asiatica Manconi and Ruengsawang, 2012 , holotype MSNG 56534a, Pong River, Thailand; Sterrastrolepis brasiliensis Volkmer-Ribeiro and De Rosa Barbosa, 1978 holotype MNRJ 0 92 (ex- MCN 113), 3 gemmules, Turvo River, branch of Paranaiba River, Paranà Basin, Goias State, Brazil. Uruguaya corallioides (Bowerbank, 1863) BMNH 1952.6.30.2, Uruguay River. MNHN DX 325, Orinoco River, 1885, M. Chaffangeon. ZMB 1703, Amazonia, ii.1892, V. Honnef.

Diagnosis. This species can be distinguished by the unique combination of morphotraits. A distinctive trait is the spicular complement of the gemmular theca. Gemmular theca strongly armed by gemmuloscleres of two categories: large, stout, spiny to smooth oxeas (megascleres size) intermingled with smooth strongyles (C-like to bean-like), both tangentially embedded in the entire thickness of the theca. Pneumatic layer absent.

Etymology. The specific epithet armata refers to the gemmular theca strongly armed by gemmuloscleres of two categories.

FIGURE. 2. Cherokeesia armata n. sp. a, Holotype in vivo encrusting a rock. b, type locality from the Nolichucky River in the Tennessee hydrographic basin.

FIGURE. 3. Cherokeesia armata n. sp. Skeleton and spicular complement of type material series from the Nolichucky and Hiwassee rivers. a, Skeletal network of megascleres. b–i, Megascleres as spiny oxeas and gemmuloscleres spiny to smooth oxeas and C- to bean-like or ovoid strongyles; see also Fig. 5 .

FIGURE. 4. Cherokeesia armata n. sp. Gemmular traits of type material series from the Nolichucky and Hiwassee rivers. a–l, Gemmule architecture and traits of the gemmular theca. A, Gemmules in a cluster. b–c, Gemmular theca (cross section). d, Gemmular surface with multiforamina, and gemmuloscleres strongyle-like in a mosaic. Foramen apertures with simple collar. e, Inner surface of gemmular theca with foraminal aperture and evident outlines of two categories of gemmuloscleres, strongyle-like and large spiny oxeas. f, Gemmular theca with thin wall of a few layers of gemmuloscleres; inner view of foraminal aperture on the right (detail of cross section). g, Gemmular theca with a mass of staminal cells (cross section). h, Magnification of the tri-layered gemmular theca of compact spongin armed by two categories of embedded spicules as small, smooth strongyles and large, stout, spiny oxeas (cross section). i, Inner layer of the theca (compact spongin) and gemmuloscleres (smooth, short strongyles) strictly adhering to each other by spongin. j, Gemmular surface. k, Small, smooth strongyles at the outer layer of the theca. l, Gemmular surface with single foraminal aperture and gemmuloscleres surrounding the basal portion of the short, simple collar.

Description. Growth form encrusting as minute cushions, 1–4 mm in thickness, largest specimen 10 cm in diameter (Fig. 2a). Consistency hard, fragile in vivo. Colour light gray in vivo, somewhat transparent; white (in alcohol). Surfac e alveolate with slight hispidation of more or less erected ectosomal spicules supporting small scattered conules. Oscules conspicuous in vivo, numerous, scattered. Inhalant apertures scattered. Ectosomal skeleton irregularly alveolate as a mesh network of mono- to pauci-spicular tracts (oxeas) supporting the dermal membrane. Choanosomal skeleton irregularly alveolate network, with mono-spicular polygonal meshes (100–200 µm in diameter) and few, scarcely developed, ascending pauci-spicular tracts. Spongin notably scanty, except for the gemmular theca and the basal spongin plate. Basal spongin plate well developed, and adhering to the flat base of gemmules. Megascleres stout, spiny oxeas 161.8 to 228 (199.5 ± 15.8) x 12.3 to 20.7 (16.6 ± 1.9) µm (standard error of the mean length = 2.2; standard error of the mean width = 0.3) with gradually pointed to abruptly pointed tips, straight to slightly bent; spines straight to recurving towards the spicule tips (Figs 3a–e, 5b). Microscleres absent. Gemmules sessile, at the sponge base, hemispherical (up to 800 µm in diameter), flat at the base (Fig. 4a– b) strictly adhering to the substrate by the basal spongin plate; single or in small clusters of 3–4 gemmules; strongly armed by tangential gemmuloscleres of two categories. Foramen single to multiforamina (up to 3) (Fig. 4d–f) with simple collar (Fig. 4l) (20–40 Μm in diameter) sometimes closed by a spongin lamina. Gemmular theca of compact spongin variably thick (25–150 Μm in thickness), tri-layered, with gemmuloscleres (up to 10 layers) of two categories intermingled and tangentially embedded (Fig. 4f–g). Outer layer of thin compact spongin, like a film on gemmuloscleres surfaces (Fig. 4j–k). Middle layer of a thin non-alveolate layer of compact spongin (pneumatic layer absent). Inner layer of compact spongin (Fig. 4e–f and i). Gemmuloscleres of two types (strongyle-like spicules and spiny to smooth oxeas). Type I. Dominant, in several layers (5–7) more or less in a mosaic-manner, joined by a conspicuous amount of compact spongin. Strongyle-like spicules 29.3 to 17.0 (22.4 ± 2.5) x 17.1 to 8.5 (10.3 ± 1.3) µm (standard deviation of the mean length = 0.3; standard error of the mean width = 0.1), stout, entirely smooth, from extremely bent C-shaped to bean-shaped up to ring-shaped or button-like (Fig. 3f–i). Rare, elongate, short typical strongyles, slightly bent to straight (50–100 x 10 µm) also present. Type II. Less abundant, large, stout, spiny to smooth oxeas tangentially embedded intermingled with gemmuloscleres type I in the entire thickness of the theca (Figs 4h, 5a). Oxeas (173.3 to 258 (219.7 ± 16.7) x 9.8 to 17.4 (14.7 ± 1.9) µm, (standard error of length = 16.7; standard error of mean width = 0.3) abruptly pointed, spiny to smooth, with acute spines straight to recurved toward the tips.

Habitat. On the underside of submerged hand size rocks to small boulders in flowing water at depths ranging from 20 to 200 cm. Gemmules were recorded only in some specimens collected during summertime.

Geographic distribution. Currently known only from the Nolichucky ( Fig. 1 ) and Hiwassee Rivers (Blue Ridge Province, Southern Appalachians) in the Tennessee River hydrographic basin.

Figures

FIGURE 1. Global biogeographic distribution of family Potamolepidae with inserts showing the distribution of Cherokeesia n. gen. within Tennessee and location of Tennessee within the United States. Approximate location of Tennessee is indicated by asterix. Fossils are indicated by plus symbol.

FIGURE 5. Cherokeesia armata n. sp. a, gemmuloscleres type I as large acanthoxeas from notably spiny to almost smooth; b, megascleres of the skeleton as stout acanthoxeas.