Poraniopsis Perrier 1891

Mah, Christopher L. & Foltz, David W., 2014, New taxa and taxonomic revisions to the Poraniidae (Valvatacea; Asteroidea) with Comments on Feeding Biology, Zootaxa 3795 (3), pp. 327-372 : 356-357

Poraniopsis Perrier 1891

Figure 9 A–F

Poraniopsis Perrier 1888: 763 (nom. nud.); 1891: K105; Fisher 1910: 568; 1911: 260–261; 1940: 158; Hayashi 1940: 166; Bernasconi 1964: 264; 1980: 253; A.M. Clark 1984: 21, 24; Clark & Downey 1992: 220

Lahillea deLoriol 1904: 32 (Type species L. mira de Loriol, 1904)

Alexandraster Ludwig 1905: 210 (Type species A. mirus Ludwig, 1905 )

Ortmannia deLoriol 1906: 78 (replacement name for Lahillea , preoccupied.)

Type species: Poraniopsis echinaster Perrier 1891 .

Diagnosis (Expanded Description below): Stellate body (R/r=1.6–3.5) with short to elongate arms. Interadial arcs angular. Abactinal and lateral skeleton reticulate with wide meshes covered by skin. Each skin filled region filled with papulae. Short, sharp spinelets present in some species, absent in others. Abactinal/lateral plates each with a large, prominent sharp conical spine with smaller secondary spines present. Marginal plates present from along lateral side from terminal to interradius, but are otherwise similar in morphology to abactinal plates. Skin covers abactinal, lateral and actinal surface, including abactinal, marginal, actinal and furrow spines, one to three (two in most).

Included species. P. echinaster Perrier, 1891 ; P. inflata ( Fisher 1906)

Taxonomic comments. Poraniopsis echinaster and P. inflata display, at best, very few morphological differences, but they appear to display a geographical distribution consistent with character differences. Poraniopsis echinaster possesses tiny, abundant spinelets within the papular membranes which are absent in P. inflata save for tiny (0.5 mm) almost sclerite-like spinelets present in the holotype of P. japonica , which is likely a character associated with its large size.

Work by Foltz et al. (2013) on the goniasterid Hippasteria phrygiana demonstrated the presence of a single species widely occuring across three ocean basins in two hemispheres. Poraniopsis has a parallel distribution pattern, including the North Pacific, the Patagonian South Atlantic/South Pacific, South Africa and the southern Indian Ocean. This suggests Poraniopsis as a second taxon for testing phylogeographic hypotheses of widely occuring benthic species.

Diagnosis. Body stellate with R/r=1.6–3.5. Arms round in cross section with no discrete actinolateral edge, disk small, interbrachial arcs angular. R/r=1.6–3.5. Arm shape variably short and wide to more elongate. Discrete layer of skin covers body surfaces, including spines.

Abactinal skeleton reticulate, open ( Fig. 9 A). Primary circlet, i.e., the ten primary radial and interradial plates on the disk and an irregular carinal series are present along each ray ( Clark and Downey 1992). Reticulations composed of overlapping closely articulated, smaller rod-shaped plates. Large (~ 0.3 cm or greater) pointed, conical spines present on skeleton throughout abactinal, marginal and actinal surface. Reticulations forming transverse rows crossing carinal series on arms. Reticulations with widely spaced skin filled regions, filled with papulae, 10–30 widely spaced throughout each mesh ( Fig. 9 C). Other variable minor accessories present in each mesh, ranging from tiny papillate spinelets to small, irregularly shaped ossicles. Madreporite strongly convex with welldeveloped sulci, sits on paired abactinal plates series bissecting interradius. Anus surrounded by spines, 10–20 forming periphery around opening.

Marginal plates indistinguishable from abactinal plates, save for their continuous tracking from the terminal plate to the plates bisecting each interradius. The widely spaced, reticulate mesh comprises the abactinal/lateral region of the non-actinal body region. As with the abactinal plates, the superomarginals each bear a large, pointed, skin-sheathed, spine on each plate. Inferomarginals with spines, one to three per plate, with notched tips, forming one to three points per spine. Intermarginal papulae present, similar in arrangement to abactinal mesh. Papulae more numerous proximally and decreasing distally.

Actinal plates in linear arrangement extending from adambulacrals to inferomarginals with tissue filled space between them ( Fig. 9 B). Prominent spines present on actinal plates ( Fig. 9 B). Grooves present along actinal plate series aligned with inferomarginal plates ( Fig. 9 D). Skin covers actinal surface including actinal and furrow spines. Furrow spines one to three per plate (most with two proximally), arranged transversely with varying lengths relative to subambulacral spines depending on species ( Fig. 9 D). Furrow spine tips with variable morphology, dependent on species-cylindrical, spatulate or with notches. Subambulacrals similar in morphology to furrow spines.

Color in life is similar in both species. Poraniopsis echinaster has been recorded as white, orange and bright to dark red ( Mutschke & Mah 2009; Clark & Downey 1992). Poraniopsis inflata is described as “cream to bright orange” with white spines ( Lambert 2000). Lamb and Hanby (2005) show this species as orange with a deeperreddish reticulate skeleton with white tips. Other specimens from British Columbia show yellow to orange coloration. Some California specimens from the Cordell Bank region possess a red to purple reticulation with a white to light colored body.

Figures

FIGURE 9. Poraniopsis A. USNM E 51288 P. inflata, Galapagos. Abactinal surface (R = 6.3). B. Actinal surface. C. Close up of abactinal surface. Papular pores, reticulate mesh. D. Close up of actinal surface. Furrow and actinal spines. E. P. mira Lectotype, MHNG-INVE- 71730. Abactinal. Scale bar = 5.0 mm. F. Close up of USNM E 5603, Holotype, P. japonica showing tiny spinelets (sp.) and papular pores (pap.). Scale Bar = 0.5 mm.