Staurocalyptus pamelaturnerae, Reiswig, 2018

Reiswig, Henry M., 2018, Four new species of Hexactinellida (Porifera) and a name replacement from the NE Pacific, Zootaxa 4466 (1), pp. 124-151 : 141-145

Staurocalyptus pamelaturnerae n. sp.

( Figs 9 & 10 , Table 5)

Material examined. Type material: Holotype: CAS 218813, ROV Hercules from EV Nautilus , dive H 1566, 26 Aug 2016, Wreck of USS Independence, side of midship gun turret, off Farallones Is., Greater Farallones National Marine Sanctuary off San Francisco, California, U.S.A., 37.4776°N, 123.1346632°W, 805.8 m, Fix 95% ethanol.

Not seen: Holotype fragment: MCZ IZ 141509, data as above.

Species diagnosis. Staurocalyptus with body of branching tubes, with veil of raised crucial hypodermal prostalia restricted to a narrow band around the oscula. Exhalant canal openings into the atrium are uncovered. Dermalia are mostly pentactins with some stauractins and tauactins; atrialia are mainly hexactins and pentactins with a few stauractins, tauactins and diactins. Discoctasters are entirely rough with great size range, 98–363 µm diameter.

Description. Body form of the holotype is that of a soft-bodied, bright yellow, branching tubular sponge hanging from attachment to metallic surface ( Fig. 9A ). Six terminal oscula on tubular body elements are recognizable on in situ images of the specimen; the body wall around larger oscula is flared or turned out trumpetlike. Tubular elements leading to the large terminal oscula are about 10 cm in diameter and 5.7–8.1 mm wall thickness. A fringe of long spicules surrounding oscular margins in situ images proved to be a short veil of smooth pentactins and diactins serving as lateral and marginal prostalia. About one-third of the specimen was collected, including the large central osculum. The author was supplied with only an oscular margin fragment ( Fig. 9B ) for analysis and description but extensive imagery of other parts were also examined. The veil of prostal pentactins and diactins extends for a short distance around the blunt oscular margin ( Fig. 9C ), 1–2 mm onto atrial surface but 7–12 mm onto the dermal surface. Diactin and pentactin prostalia extend in groups from small conules spaced about 100 µm apart. The dermal surface beyond the veil is smooth, without either emergent or subdermal large diactins or hypodermal pentactins but some conules may still occur there. Whether the lowest parts of the body near the site of attachment bear more prostalia is unknown and will have to wait for further sampling of this species.

Beneath the raised hypodermalia, the dermal lattice, a fine-meshed grid of mostly pentactin (85%) and a few stauractin (11%) lateral rays, spans across inhalant canals; no hexactins were found in small fragments from the dermal tissue. In contrast, the atrial surface has exhalant canals widely open to the atrium and uncovered by a lattice of atrialia or hypoatrialia; the atrial lattice is tightly bound on the atrial surface between exhalant canals and it is composed of mostly hexactins (57%), a smaller proportion of pentactins (32%) and small numbers of stauractins, triactins and diactins. Many atrialia with a short spherical remnant of the sixth ray, at least twice the diameter of lateral rays, are here considered unusual pentactins and counted as such. The branched holotype is calculated from laser scales to have been 88.9 cm long by 39.9 cm wide; only a small portion was collected and the author was provided with a 11.8 x 4.6 cm subsample of that ( Fig. 9B ) for preparing this description. Color of the fragments preserved in ethanol is light tan. The known distribution of the species is the type location on the sunken USS Independence in the Farallones Sanctuary off San Francisco, California, at a depth of 804.9 m.

Megascleres (for measurements see Table 5) consist of a variety of diactins (prostalia and three size classes of choanosomals), hypodermal pentactins, dermalia and atrialia. Prostal diactins ( Fig. 10A ) are the longest and thickest spicules, usually gently curved and reaching nearly 17 mm; their tips are smooth and rounded. Hypodermal pentactins ( Fig. 10B ) are regular and crucial in form with rays approximately equal in length. Tangential ray ends are parabolic but proximal rays tapered to a sharp point; all ray ends are subterminally rough. Choanosomal diactins ( Fig. 10C ) are the most common spicules of the body; they are smooth. straight to gently curved, mostly smooth with rough rounded ends. Dermalia ( Fig. 10D ) are mostly pentactins (85% of 101) and stauractins (11%) and a few tauactins; hexactins occur but are rare (<1%). These spicules are entirely rough, have cylindrical rays and rounded rough tips. Atrialia ( Fig. 10E ) are mostly hexactins (57%) and pentactins (32%) with few stauractins (2.5%) and rare tauactins and diactins.

Microscleres (for measurements see Table 5) are, in order of descending abundance, hemioxyhexasters (39% of 300), microdiscohexasters (33%), oxyhexasters (13%), oxyhexactins (10%), and discoctasters (only 5.3% but dominant by size). Microdiscohexasters ( Figs 10F, G ) are typical for an acanthascinine, with primary and secondary rays about equal in length, entirely smooth, ~20 µm in diameter, with numerous terminal rays, counted here as 28– 32 –35. Oxy-tip microscleres, including hemioxyhexasters ( Fig. 10H ), full oxyhexasters ( Fig. 10I ) and oxyhexactins ( Fig. 10J ), have 1–4 straight and tapered secondary rays on each primary ray; the rays are smooth with very sharp tips. Discoctasters ( Figs 10K–L ) vary greatly in size. It is likely that several size classes occur here but a very large number of measurements would be needed to show them. The primary rays each bear 1–5, most commonly 3-4, slightly splayed but straight terminal rays that end in small but clear terminal discs ( Fig. 10L magnified ray tip). These spicules are entirely covered by small reclined spines; it is not uncommon to encounter spicules with single terminal rays developed outside the eight normal primary rays.

Remarks. This specimen is clearly a member of Staurocalyptus by possession of discoctasters and hypodermal pentactins without thorns. It differs from all 17 known species by several characters. The hypodermal pentactins are much smaller than those of S. affinis Ijima, 1904 , S. celebesianus Ijima, 1927 , S. glaber Ijima, 1897 , S. pleorhaphides Ijima, 1897 , S. roeperi ( Schulze, 1886) , and S. solidus Schulze, 1899 . They are much larger than those of S. fuca Tabachnick, 1989 , S. hamatus Lendenfeld, 1915 , S. heteractinus Ijima, 1897 , S. microchaetus Ijima, 1898 , and S. tylotus Reiswig & Stone, 2013 . They are all crucial while 69% of those in S. psilosus Reiswig & Stone, 2013 are paratropal. Of the remaining five species with hypodermal pentactins similar to those of this species, they all differ in having atrialia as only hexactins, without pentactins; these are S. dowlingi ( Lambe, 1894) , S. entacanthus Ijima, 1904 , S. fasciculatus Schulze, 1899 , S. rugocruciatus Okada, 1932 , and S. tubulosus Ijima, 1903 . These differences, among others too numerous to list, verify that the specimen is the holotype of a new species, here designated as Staurocalyptus pamelaturneri .

Etymology. This species is named after Pamela Turner, the wife of a member of the Greater Farallones National Marine Sanctuary whose financial donation to the Greater Farallones Association made description of this new species possible.

Figures

FIGURE 9. Staurocalyptus pamelaturnerae n. sp. body. A. Encircled specimen in situ on USS Independence prior to sample collection by ROV. B. Facial views of dermal (above) and atrial (below) surfaces of the fragment available for analysis. C. Longitudinal section of the oscular margin (dermal right, atrial left) showing the narrow distribution of diactine prostalia and emergent pentactine hypodermalia. D. Small conules at the emergence points of diactins and pentactins. E. Atrial surface of the vestibule with open, uncovered exhalant canal apertures. F. Dermal lattice over inhalant canals and subdermal spaces. G. Atrial lattice tightly bound to underlying tissues between exhalant canals.

FIGURE 10. Staurocalyptus pamelaturnerae, n. sp. holotype spicules. A. A prostal diactin and enlargements of the end. B. Two hypodermal pentactins with enlargements of ray ends. C. Two choanosomal diactins and four enlarged ends. D. Dermalia, pentactin and stauractin with enlarged ray ends. E. Atrialia, pentactin and hexactin. F. Microdiscohexaster at same scale as other microscleres, and enlarged terminal ray end. G. Microdiscohexaster enlarged to show detail. H. Hemioxyhexaster. I. Oxyhexaster. J. Oxyhexactin. K. Small discoctaster. L. Large discoctaster with magnified secondary ray end.