Pheronema raphanus Schulze, 1895

Tabachnick, Konstantin, Fromont, Jane, Ehrlich, Hermann & Menshenina, Larisa, 2019, Hexactinellida from the Perth Canyon, Eastern Indian Ocean, with descriptions of five new species, Zootaxa 4664 (1), pp. 47-82 : 49-52

Pheronema raphanus Schulze, 1895

Material examined. Australia: Western Australia: WAM Z35337, Z98331, Z98330, respectively – 2 specimens and 1 lot (4 fragments), Perth Canyon (31 o 59’33”S, 115 o 10’59’’E to 31 o 00’07”S 115 o 10’41’’E, Figure 1 ), 508– 478 m, J. Fromont and C. Whisson, sled, 29/11/2005, RV Southern Surveyor station SS1005/068.

Type material: off Andaman Islands : (12 o 37’N, 92 o 19’E), 530 m, RV Investigator , station 210, ( NMHUK 1896.09.12.002; HM 5861) .

Other material: Western Indian Ocean: 4 specimens (6 o 53.1’N, 93 o 35.5’E), 752 m, RV Valdivia , station 210, ( HM 5675, HM 5676, HM 5677, HM 5678, HM 5680). Western Indian Ocean: 4 specimens (7 o 48.8’N, 93 o 7.6’ E), 752 m, RV Valdivia , station 211, ( NHMUK 1908.09.24.044, HM 3703, HM 4351, HM 5674). Off Philippines: 3 specimens (13 o 2.8–2.9’N, 122 o 37.1 to 122 o 35.5’E), 805 m, Musorstom 2, station 39, ( MNHN 4243, MNHN 4244, MNHN 4245). East China Sea, off southern Japan: 3 specimens (30 o 45.8’N, 128 o 04.8’E) 499– 492 m, 1/11/1955, RV Vitiaz 22, station 3540, ( IORAS 5/2/1329; IORAS 5/2/sp4112; ZINRAS sp2218). Off Philippines: 2 specimens (8 o 40’N, 119 o 48’E), 850 m, 3/1/1975, RV Vitiaz 57, station 7242 ( IORAS 5/2/sp3320).

Description. Body, Figure 2 . The specimens are conical and taper to a narrow base; the atrial cavity (osculum) is shallow or nearly absent (≤ 10 mm deep). The WA specimens are from 35–80 mm high and 12–45 mm maximum diameter. The osculum is ≤ 20 mm diameter. Prostalia lateralia appear as several tufts around the sponge maximum circumference ( Figure 2 ), they extend outwards to 20 mm from the surface. Prostalia basalia are presented by tufts at the lower part of the body up to 40 mm long ( Figure 2 ).

Spicules. Megascleres Figure 3 , Table 3. Choanosomal spicules are pentactins with rays often of different lengths and outer ends conically pointed or rarely rounded; the rays are 0.08–1.90/ 0.009 –0.144 mm ( Figure 3 B–C). Uncinates are of two types: normal form which have identical conically pointed outer ends 0.6–2.3/ 0.004 –0.007 mm, and those with one outer end conically pointed and the other rounded 0.5–0.8/ 0.005 mm ( Figure 3 G–H). One specimen has a potential precursor of uncinates – hexactinic spicules with rays covered by harpoon–like spines, in these spicules some of the rays are short and rudimentary, rays are 0.045–0.30/ 0.005 mm ( Figure 3 I ). Basalia (about 70/ 0.015mm) are two-toothed anchorate spicules, they rarely have one tooth, their shafts are spiny ( Figure 3 D–F). Prostalia lateralia (about 40/ 0.04 mm) are diactins with conically pointed outer ends, their shafts are partly smooth and partly rough ( Figure 3 A ). Dermal and atrial spicules are pinular pentactins and some hexactins, occasionally it is possible to find their derivatives only by the tangential rays or the pinular ray ( Figure 3 J–O). The pinular ray is ovoid in shape, tangential rays are conically pointed, stout or lanceolate, often spiny or rarely smooth. In tangential plane the rays have the shape of a regular cross or sometimes an x-shape ( Figure 3 M–N). A peculiar feature of the dermal and atrial pinular pentactins is the presence of spines situated at the site of the reduced ray ( Figure 3 J–K). The pinular ray of the dermal pentactin is 0.015 –0.111 mm long, tangential rays are 0.019 –0.063 mm long, the diameter of these rays is 0.002 –0.005 mm. The pinular ray of the atrial pentactin is 0.030 –0.100 mm long, tangential rays are 0.030 –0.059 mm long, the diameter of these rays is 0.002 –0.005 mm.

Microscleres, Figure 3 , Table 3. Amphidiscs are of two types: macramphidiscs and micramphidiscs. The macramphidiscs are 0.070 –0.215 mm long, the umbel length is 0.019 –0.076 mm long, the umbel diameter is 0.019 –0.078 mm ( Figure 3 Q–V). The shafts of the macramphidiscs are tuberculated, the teeth of the umbels are often of different size so sometimes the spicules can be referred to as paradiscs. The micramphidiscs are 0.013 –0.062 mm long, the umbel length is 0.003 –0.018 mm long, the umbel diameter is 0.004 –0.014 mm ( Figure 3 W–AA). The shafts of the micramphidiscs are tuberculated or rough, the umbels of these spicules are often of different sizes so the spicule can be called a hemidisc. One or two umbels may have spherical widening or no tooth, termed a tylodisc or paraclavule for the former case and tylodiactin for the latter type of spicule. Some micramphidiscs are paradiscs. Oxyoidal microscleres are hexactins and pentactins, the latter often with a rudimentary ray ( Figure 3 AB–AC). Sometimes one ray of these microscleres has several long spines, usually this ray is longer, and it may be that such spicules should be considered as canalaria hexactins. The ray of the oxyoidal microscleres is 0.018 –0.067 mm.

Remarks. This species was previously known to be distributed in the central and western Indian Ocean ( Schulze, 1894; 1904) and the Philippines ( Lévi and Lévi, 1989). This new record from the eastern Indian Ocean fills a gap in a previously disjunct species distribution. The newly found representatives are attributed to Pheronema raphanus due to the body shape with a shallow atrial cavity and tapering body, and general similarity of the spicules, specifically the shape and size of the pinular pentactins and two types of amphidiscs. There are also a number of differences in the spiculation of the eastern Indian Ocean specimens compared to previous descriptions. These differences are: two types of uncinates, irregular size of the tooth of macramphidiscs with tuberculated shafts, different sizes of umbels in some micramphidiscs, sizes of the pinular spicules and both types of amphidiscs. Pinular pentactins in these specimens of P. raphanus have spines situated at the site of the reduced ray.

The reinvestigation of previously described specimens of P. raphanus showed that those collected off the Philippines and described by Lévi & Lévi (1989) and those from the East China Sea also have some differences from the type specimens (off Andaman Island) and the specimens from the eastern Indian Ocean (Table 4). The East China Sea specimens have larger dermal and atrial pentactins and larger macramphidiscs. Some of the largest dermal and atrial pentactins have a pinular ray with spines situated approximately two thirds along the ray in the basal part (similar to P. weberi Ijima, 1927 ). The specimens off the Philippines have stout macramphidiscs with a central whorl of tubercles, the specimens from the East China Sea have similar tuberculated macramphidiscs to those in the specimens from off Western Australia. A specimen IORAS 5/2/sp3320 has an additional unique feature with the atrial pentactins notably larger than the dermal ones. It is likely that subspecies status for these geographically and morphologically different specimens of P. rhaphanus may be appropriate in future.

Distribution. This species was first recorded from off the Andaman and Nicobar Islands and has also been reported from the Eastern Philippines. This record from the Perth Canyon extends the distribution southward in the Indian Ocean.

Figures

FIGURE 1. Map of Perth Canyon. Triangles are RV Falkor stations and circles are RV Southern Surveyor stations.

FIGURE 2. Pheronema raphanus WAMZ98331 external morphology (scale 60 mm).

FIGURE 3. Spicules of Pheronema raphanus. WAMZ35337. A, prostalia lateralia diactine. B–C, choanosomal pentactins. D–F, prostalia basalia anchors. G–H, uncinates. I, hexactinic precursor of uncinate. J, dermal pinular pentactine. K atrial pinular pentactin L. hexactin. M–N, tangential rays of dermal pinular pentactins. O, abnormal dermal spicule with a distal pinular ray. P, canalaria hexactin. Q–V, macramphidiscs. W–AA, micramphidiscs: W, hemidisc; X, tylodiactine; Y, normal micramphidisc; Z, paradisc; AA, tylodisc. AB–AC, microxyhexactins.