CHONDROCLADIA THOMSON, 1873

Hestetun, Jon Thomassen, Tompkins-Macdonald, Gabrielle & Rapp, Hans Tore, 2017, A review of carnivorous sponges (Porifera: Cladorhizidae) from the Boreal North Atlantic and Arctic, Zoological Journal of the Linnean Society 181, pp. 1-69 : 13-16

SUBGENUS CHONDROCLADIA THOMSON, 1873

Diagnosis: Chondrocladia without a layer of special spicules (subtrochirhabds or trochirhabds), lacking special rostriform (snoutlike) subtylostyles in filaments or terminal balls, and without planar vanes formed of evenly spaced upright branches (from Lee et al., 2012).

Type species: Chondrocladia virgata Thomson, 1873 (by monotypy).

Remarks: Genus Chondrocladia is diagnosed as Cladorhizidae with anchorate isochelae and currently contains the subgenera Chondrocladia , Meliiderma Ridley & Dendy, 1887 and Symmetrocladia Lee et al., 2012 . Only subgenus Chondrocladia is present in the North Atlantic and Arctic.Molecular evidence ( Hestetun et al., 2016b) suggests that subgenus Chondrocladia is polyphyletic with regards to the two other subgenera in the genus roughly corresponding to the informal grouping into ‘concrescens’ and ‘Crinorhiza’ type morphologies (e.g. Ridley & Dendy, 1886; Topsent, 1930; Tendal, 1973), the former being stem- or club-shaped while species of the latter type are typically stalked with a spherical or subspherical body. The two species treated here belong to the ‘concrescens’ type.

CHONDROCLADIA (CHONDROCLADIA) GRANDIS ( VERRILL, 1879)

( FIGS 10, 11; TABLE 2)

Original description: Cladorhiza grandis Verrill, 1879: 204 .

Synonyms and citations: Desmacidon arcticum , D. clavatum , D. giganteum , D. nucleus Hansen, 1885: 14 ; Cladorhiza nobilis Fristedt, 1887: 456 ; Chondrocladia gigantea ( Lundbeck, 1905: 102; Topsent, 1913: 48; Hentschel, 1929: 936; Burton, 1930: 492; Topsent, 1930: 28; Brøndsted, 1933: 11; Koltun, 1959: 83; Tendal & Barthel, 1993: 12; Tendal, Barthel & Tabachnick, 1993: 12; Tendal & Sahling, 1997: 16; Kübler & Barthel, 1999: 290); C. concrescens in part ( Koltun, 1970a: 190). Not: C. gigantea ( Boury-Esnault, Pansini & Uriz, 1994: 100) .

Type material examined: Lectotype: Sch. ‘ Wachusett’ , USNM 8462 (Gloucester fisheries, 1879, Western Bank, 43°17ʹN, 060°58ʹW, 329 m) . Paralectotypes: Gloucester Fisheries, Sch. ‘Marion’, YPM 6987 (1879, Banquereau, 375–550 m) ; the Norwegian North-Atlantic Expedition, st. 48 (6 August 1876, 64°36ʹN, 010°22ʹW, 547 m), st. 57, st. 58 ZMBN 121 , st. 137 (21 June 1877, 67°24ʹN, 008°58ʹE, 827 m) .

Other material examined: Gloucester Fisheries 1879–1880, Sch. ‘Albatross’ 1884, the Danish Ingolf Expedition, M/S ‘Michael Sars’ 1902, M/S ‘Thor’ 1903, ‘Tjalfe’ Expedition, Godthaab Expedition, ‘Sotra’, R/V ‘Johan Ruud’, BIOFAR, R/V ‘Paamiut’ 2004–2013, EU Flemish Cap 2007, CCGS ‘Hudson’ 2007, LAR2012 (see Supporting information).

Comparative material examined: Chondrocladia (Chondrocladia) verticillata Topsent, 1920 (USNM 975, 31180).

Diagnosis: Erect, club-shaped sponge with branched root, basal stem and elongated upper part with numerous secondary processes terminating in inflatable spherical structures. Megascleres two categories of mycalostyles and acanthostyles. Microscleres anchorate unguiferous isochelae of two size classes with six and six to nine teeth, respectively, and sigmancistras.

Description: Large, erect, club-shaped sponge with well-developed branching root-like structure, basal stem and elongated, enlarged upper part set with numerous short or branch-like processes projecting in all directions from the stem. May reach a length of at least 60 cm ( Tendal & Barthel, 1993). Basal stem part is usually partly covered in sediment giving a slightly coarse, dark brown appearance, while the upper part is lighter in colour, with a slightly larger diameter. Surface slightly hispid. Processes typically 1–7 cm long and 2–4 mm in diameter, sometimes reduced to wart-like knobs, and terminate in translucent inflatable spheres that deflate during collection. Spheres are maintained by a remnant aquiferous system with canals inside the main stem and are used both for prey capture and reproduction ( Kübler & Barthel, 1999). Colour of the upper part is white to very lightly brown in situ or in freshly collected specimens and yellowish to light brown in ethanol.

Numerous specimens of this species were examined, including two specimens specifically mentioned by Verrill (1879): USNM 8462, here designated as the lectotype, 18.5 cm tall with almost all of the root missing; an 8.5 cm long and 1 cm in diameter stem part and a 10 cm long and 1.5–2 cm in diameter top part torn off at the apex. Branches have detached showing insertion points into the main body ( Fig. 10A). The specimen is in a fragile state, with the outer layer starting to detach from the stem core. Paralectotype YPM 6987 a 10.5-cm-tall specimen with an incomplete root system, a 6 cm long and around 1.5 cm in diameter stem part, and a 4.5-cm-long and 2 cm in diameter damaged upper part. Several branches have detached from the specimen after preservation ( Fig. 10B). The types of Desmacidon giganteum , D. arcticum, D. Clavatum and D. nucleus erected by Hansen (1885) and later synonymized as Chondrocladia gigantea by Lundbeck were also re-examined. Paralectotype ZMBN 121, corresponding to Hansen (1885) Pl. VII, Fig. 8, is re-described here: The specimen is 22 cm tall. Lower stem 11 cm long and 1 cm in diameter; upper part is 11 cm long and 2 cm in diameter. Projections are shorter, almost wart-like, and spaced farther apart than in the examined specimens from the NW Atlantic ( Fig. 10C). In situ images were obtained of a specimen collected on the Nova Scotia shelf by the 2007 CCGS ‘Hudson’ cruise: 14.5 cm tall, with a 7.5-cm-long and 1 cm in diameter stem part and a 7-cm-long and 1.5 cm in diameter upper part. The root system, with rhizoids up to 10 cm in length, was recovered ( Fig. 10D, E). Two additional specimens, YPM6874 (NW Atlantic) and NTNU15204 ( Svalbard), are also pictured ( Fig. 10F, G).

Skeleton : Main stem consists of a central, dense core of closely packed bundles of mycalostyles wound in a rope-like spiral pattern around the axis that becomes less pronounced in the upper part of the stem. Around the central core is a clearly separated outer tissue layer supported by mycalostyles and containing numerous isochelae. The stem and outer layer are loosely connected with lacunose soft tissue containing canals and choanocyte chambers. The outer layer of the basal stem and roots contains acanthosubtylostyles mixed with a fine layer of sediment.

Processes are composed of a rigid central stem composed of overlapping mycalostyles, and a tough outer layer of longitudinally arranged mycalostyles with a lacunose layer of less dense tissue in between. This middle layer contains a radial spoke-like supporting skeleton except in the swelling, where mycalostyles are fewer and more confusedly arranged, allowing inflation. The central stem goes through the inflatable swelling and terminates the process in a small brush-like point. Longitudinal canals are found in both the internal, less dense tissue and in the outer skeleton. Mycalostyles are set perpendicular to the longitudinally arranged mycalostyles in the outer layer and project slightly from the surface. Both types of isochela are present, with large isochelae most common at the surface. Bundles of sigmas are found in the swelling ( Fig. 11A–C).