Janulum imago Kelly
Creators: name: Kelly, Michelle
name: Erpenbeck, Dirk
name: Morrow, Christine
name: Soest, Rob Van
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Porifera
Demospongiae
Poecilosclerida
Raspailiidae
Janulum
Janulum imago

description: Janulum imago Kelly & van Soest sp. nov.   
(Fig. 1, 3 B–F, Table 1)  
 Material examined. Holotype—NIWA 94196, Paratypes—NIWA 93421, 94185: TAN1402/31, Lot 224, Forde Guyot, Louisville Seamount Chain, International Waters, 35.317° S, 170.452° W, 1205–1600 m, 11 Feb 2014, collected by epibenthic sled from RV Tangaroa.   
 Type location. Forde Guyot, Louisville Seamount Chain.   
 Distribution. Known only from Forde Guyot, Louisville Seamount Chain.   
 Description. Thinly encrusting in the interstices of stony coral Solenosmilia variabilis (Fig. 3 C), holotype, about 4 cm length, 2 cm wide and 1–2 mm thick. Surface follows undulations of coral substrate and is punctate with flush oscules 1 mm diameter. Larger, elongate openings are also present (Fig. 3 D). Interior cavernous. Texture in life firm, crisp, but very delicate and friable. Colour in life is translucent pale blue (Fig. 3 C).   
 Skeleton. Choanosome and ectosome a cavernous, extremely fragile isodictyal reticulation of megascleres (Fig. 3 E, F). Ectosome undifferentiated from underlying choanosome, consisting of a tangential isodictyal reticulation with the ends of spicules visible occasionally, protruding from the surface membrane (Fig. 3 D).   
 Spicules. Megascleres—Strongyles (Fig. 3 B, F; Table 1), faintly to acutely curved at each end, ends are orientated towards the same side or opposite sides of the spicule. Perfectly straight spicules and those with an acute bend at only one end are less common. Some spicules are slightly sinuous. Lightly spined, concave spines project perpendicular to the shaft, aligned in short spiralling linear arrays, ends rounded and smooth, slightly enlarged. Spines appear to be hollow in some spicules, 278 (240–320) x 15 (10–18) µm.   
 Substrate, depth range and ecology. Encrusting the interstices of dead stony coral rubble of the species S. variabilis, a CITES protected species and important habitat former in deep water around New Zealand (Tracey et al. 2011). Forde is an elongated guyot, a seamount with a flat top, oriented northwest-southeast with a summit plateau at 1000–1100 m deep with flanks that are deeply incised with gullies and ridges. The plateau edge and upper flanks are exposed bedrock with sand and intact stony coral (Clark et al. in press 2015).   
 Etymology. Named for the “echo” of the genus Janulum, first recorded from the Late Eocene in the region of Zealandia that formed the Oamaru Diatomite, now found living on the Louisville Seamount Chain (imago, echo; L.).   
 Remarks. Janulum imago sp. nov. is a small, fragile sponge, inhabiting a similar deep-water dead coral habitat to the genus type J. spinispiculum in the Mediterranean (Boury-Esnault et al. 1994; Calcinai et al. 2013). The spined strongyles are remarkably similar in their overall shape and ornamentation to those of J. spinispiculum (c. 200–240 µm), but those of J. imago sp. nov. are almost 100 µm longer and are double the thickness. The spicules of J. imago sp. nov. are also much longer than the spicule of J. princeps sp. nov. illustrated in Hinde & Holmes (1892: 160 µm long x 8 µm thick), clearly differentiating it from the fossil species.
description: Published as part of Kelly, Michelle, Erpenbeck, Dirk, Morrow, Christine & Soest, Rob Van, 2015, First record of a living species of the genus Janulum (Class Demospongiae) in the Southern Hemisphere, pp. 255-266 in Zootaxa 3980 (2) on pages 263-264, DOI: 10.11646/zootaxa.3980.2.6, http://zenodo.org/record/236017