Grantessa borojevici, Van Soest & De Voogd, 2015

Grantessa borojevici View in CoL sp. nov.

Figures 60a–g View FIGURE 60

Material examined. Holotype ZMA Por. 09164, Indonesia, Nusa Tenggara, Komodo, E side, Selat Linta , 8.5433°S 119.6133°E, depth 150 m, Van Veen grab, coll. R. W.M. van Soest, Indonesian-Dutch Snellius II Expedition stat. 081/ VI/01 , 18 September 1984. GoogleMaps

Description. Group of small hairy tubes ( Fig. 60a View FIGURE 60 ) rising from a common base. Life color white, in alcohol dirty white. Individual tubes with hispid surface, Sycon -like in appearance, but without oscular fringe, approximately 1 cm in height 3–4 mm in diameter. Overall size of specimen 2 x 2 x 1 cm. Consistency soft.

Histology. Syconoid aquiferous system ( Fig. 60b View FIGURE 60 ).

Skeleton. Articulate ( Fig. 60b View FIGURE 60 ). Ectosomal cortex consisting of a single layer of equiangular triactines and bouquets of diactines marking the distal cones of the choanosomal tubes. The choanosomal skeleton is formed by the longer paired actine of the pseudosagittal subectosomal triactines and the centrifugal unpaired actines of sagittal tubar triactines. As the wall of the individual ‘person’ is thin, only few tubar triactines are present, 2–3 on average, in places only a single tubar spicule is found. Tubar triactines often have slightly wavy paired actines. Near the atrial surface there are layers of subatrial triactines similar in shape to the tubar triactines, but with straight paired actines, not wavy. Atrial skeleton a single layer of predominantly tetractines (with a minority of triactines), with the apical actine protruding slightly into the atrial cavity.

Spicules. ( Figs 60c–g View FIGURE 60 ) Equiactinal triactines, pseudosagittal triactines, sagittal triactines, sagittal tetractines, diactines.

Diactines from the distal cones ( Fig. 60c View FIGURE 60 ), lance-shaped, 258– 295.3 –342 x 7– 9.6 –12 µm.

Cortical equiactinal triactines ( Fig. 60d View FIGURE 60 ), small, frequently with differences in actine lengths between the three actines of a single spicule, and also the angle of the actines may vary, 57– 97.7 –121 x 5.5– 6.5 –9 µm.

Pseudosagittal triactines ( Fig. 60e View FIGURE 60 ), unpaired actines tending to be elongated-conical, 63– 92.2 –126 x 6– 7.8 –9 µm, longest paired actine 91– 159.3 –204 x 6.5– 7.4 –8.5 µm, shortest 84– 110.1 –135 x 6– 7.2 –8 µm.

Sagittal tubar and subatrial triactines ( Fig. 60f View FIGURE 60 ), with relatively long tapering unpaired actines and short abruptly curved paired actines, unpaired actines 116– 194.7 –241 x 6– 7.6 –10 µm, paired actines 59– 82.6 –129 x 6– 6.8 –8 µm.

Sagittal tetractines ( Fig. 60g View FIGURE 60 ), usually with an elongated unpaired actine and short apical actines, but occasionally small tetractines may be more or less equiactinal, unpaired actines 63– 201.4 –315 x 6– 6.8 –8.5 µm, paired actines 81– 129.6 –165 x 6– 7.0 –8.5 µm, apical actines 9– 17.6 –45 x 5– 6.1 –7 µm.

Ecology. The material is from upper bathyal depth, 150 m.

Distribution. Indonesia.

Etymology. Named after Professor Radovan Borojevic, to honour him for his life long contribution to Calcarea systematics.

Remarks. The genus Grantessa is large, with 26 accepted species listed by Van Soest et al. (2015), the majority of which were described from Australia and Japan. We compare here our new species with representatives of the genus that show similarities with it and for completeness sake we also point out differences with other Indo-Pacific species.

Four species show general similarity in spiculation with our new species: Australian Grantessa intusarticulata ( Carter, 1886) (p. 45, as Hypograntia ) has a characteristic ectosomal palisade of microdiactines (75–90 µm), unlike the bouquets of larger diactines in our new species, and it has robust atrial tetractines dissimilar to those of G. borojevici sp.nov. Grantessa boomerang (Dendy, 1893) (p. 82, as Sycon ) also has small diactines (80 µm) and the apical rays of the tetractines are boomerang-shaped. Japanese Grantessa nemurensis Hôzawa, 1929 (p. 315) is a large mass of stiff tubes, rather different from our new species in habitus, and the apical actines of the atrial tetractines may grow as long as 480 µm. The species occurs in northern Japan (Hokkaido), well away from tropical waters. South African shallow-water Grantessa ramosa ( Haeckel, 1872) as redescribed by Borojevic (1967b: 204) has the unpaired actines of tubar triactines and tetractines distally swollen and the paired and apical actines very short, unlike those of our new species.

The new species shows some resemblance with the Australian Grantessa hirsuta ( Carter, 1886) (p. 41, as Hypograntia ), Grantessa hispida Dendy, 1893 (p. 107), Grantessa sacca Von Lendenfeld, 1885 (p. 1098), Grantessa gracilis ( Von Lendenfeld, 1885) (p. 1111, as Vosmaeria ), the Palau shallow-water Grantessa plumosa ( Tanita, 1943) (p. 404 as Sycon ), the Japanese shallow-water Grantessa shimoda Tanita, 1942 (p. 40), and the Japanese bathyal species Grantessa sagamiana Hôzawa, 1916 (p. 8), but all these differ in shape as they are a single ‘person’, and the sizes of their diactines clearly exceed that of our species as they reach 700–3000 x 16–80 µm. South Australian Grantessa spissa ( Carter, 1886) (p. 54, as Heteropia ), Grantessa pluriosculifera ( Carter, 1886) (p. 52, as Heteropia ), Grantessa polyperistomia ( Carter, 1886) (p. 47, as Heteropia ), Grantessa erinaceus ( Carter, 1886) (p. 130, as Leuconia ), and Japanese Grantessa mitsukurii Hôzawa, 1916 (p. 23) have no tetractines and spicule sizes are much larger, while South African Grantessa rarispinosa Borojevic, 1967 (p. 207) likewise has no tetractines while its spicules are smaller than those of our new species. Japanese Grantessa parva Tanita, 1942 (p. 38), lacks diactines and overall spicule sizes are smaller, whereas Japanese Grantessa basipapillata Hôzawa, 1916 (p. 19), likewise lacking diactines, has overall slightly larger spicules. Australian Grantessa erecta ( Carter, 1886) (p. 53, as Heteropia ), Grantessa compressa ( Carter, 1886) (p. 51, as Heteropia ) and Japanese Grantessa ampullae Hôzawa, 1940 (p. 38), have neither diactines nor tetractines.