Latrunclava Kelly, Reiswig & Samaai

Kelly, Michelle, Sim-Smith, Carina, Stone, Robert, Reiswig, Toufiek Samaai Henry & Austin, William, 2016, New taxa and arrangements within the family Latrunculiidae (Demospongiae, Poecilosclerida), Zootaxa 4121 (1), pp. 1-48 : 33-34

Genus Latrunclava Kelly, Reiswig & Samaai gen. nov.

Type species. Latrunclava imago gen. et. sp. nov., designated herein.

Diagnosis. Thickly encrusting Latrunculiidae with two microsclere forms: 1) anisodiscorhabds with manubrium, basal whorl, median whorl and apical whorl; 2) several size categories of long anisoconicorhabds, with manubrium and basal whorl, apical whorl and apex, and lightly acanthose shaft, and spines arrayed irregularly between the ends of the spicule, around the shaft. Megascleres are sinuous anisostyles, acanthose on the head. Ectosomal skeleton consists of a paratangential layer of megascleres above which is a palisade of anisodiscorhabds. The choanosome is a wispy irregular polygonal reticulation of megascleres. Anisoconicorhabds are scattered without orientation, throughout the outer choanosome, and across the ectosome.

Etymology. Named for Latrunculiidae with a new form of sceptre that resembles a spined or knobbed cudgel (clava, knobbed club; L.)

Remarks. Species in the new genus Latrunclava are characterised by the possession of a second form of microsclere in addition to the normal anisodiscorhabds: the sceptre-like anisoconicorhabd in several size categories, with manubrium and basal whorls, apical whorl and apex, but which lacks a median and subsidiary whorl. This form of sceptre extends between the basal whorl and apical whorl with a lightly acanthose shaft covered irregularly in sharp, single or palmate spines; the spines rarely form whorls around the shaft. All size categories of these sceptres are much longer than the ‘normal-length’ anisodiscorhabd and are scattered throughout the choanosome and ectosome without particular orientation. The anisodiscorhabds of Latrunclava gen. nov superficially resemble those in species of Latrunculia (Uniannulata) subgen. nov., with manubrium, basal and median whorls, and an apical whorl, but both lack a subsidiary whorl and apex.

The new genus Latrunclava can be compared to Sceptrella which also has a second form of sceptre-like microsclere, the isoconicorhabd (Samaai & Kelly 2002), also scattered throughout the choanosome and ectosome without orientation. The key differences are, however, the form of the sceptre (equiended in species of Sceptrella and inequiended in the species of Latrunclava gen. nov.), and there is usually only one size category of isoconicorhabd in Sceptrella spp. With the exception perhaps of S. insignis ( Topsent, 1890) , the isoconicorhabds of Sceptrella species have basal and apical whorls of spines or serrated crowns that are virtually identical to each other; they do not, in any way, resemble an anisoconicorhabd. On the other hand, the anisoconicorhabd of Latrunclava gen. nov. has a clear manubrium, basal whorl, apical whorl and apex, but is extended between these features by a shaft of irregularly placed spines.

The anisodiscorhabds of Latrunculia oamaruensis Hinde & Holmes, 1892 , named for several microfossil spicules in the New Zealand Late Eocene Oamaru Diatomite, also bear a general likeness to the anisoconicorhabds of Latrunclava gen. nov. ( Fig. 12 C) in that they are also inequiended. The key difference between the spicules of Latrunclava gen. nov. and the microfossil spicules is, however, differences in the morphology of the base of the microsclere, which in L. oamaruensis is a blunt extension of the shaft terminating with whorls of small spines. These fossil microscleres are more strongly reminiscent of the anisodiscorhabds of L. (L.) multirotalis Topsent, 1927 and L. (L.) tetraverticillata Mothes, Campos, Eckert & Lerner, 2008 , which also have multiple whorls around the shaft, but these are plate-like.

Several other microfossil spicules that closely resemble those of L. (L.) multirotalis and L. (L.) tetraverticillata , have been described and illustrated by Hinde & Holmes (1892: 218; Pl. 11, Fig. 36, 37) and Bukry (1979: Pl. 6, Fig. 12 , 13 ). Furthermore, L. apicalis Ridley & Dendy, 1886 and L. biformis Kirkpatrick, 1907 also have second, larger forms of multi-whorled or spined microscleres. Currently, L. apicalis , L. multirotalis , L. biformis , and L. tetraverticillata are placed in the subgenus Latrunculia but the possession of a second category of microsclere is unusual enough to potentially warrant the establishment of another new subgenus in the future. Until further study can be made of these and other species in the context of Sceptrella and Latrunclava gen. nov., we hereby remove the four species, L. apicalis , L. multirotalis , L. biformis , and L. tetraverticillata , from the subgenus Latrunculia ( Table 9 ). Figure G illustrates the diagnostic microscleres that define Latrunclava gen. nov.

Figures

FIGURE 12. Morphology, megascleres and microscleres of Bomba tricincta (Hentschel, 1929) gen. nov., comb. nov.: A. Illustration of holotype ZMB Por 7851 from Northern Norway, 198 m (from Hentschel (1929, Pl. 12, Fig. 3); B. Large, thick tracts of megascleres, scale = 500 µm; C. Anisostyle, slightly sinuous, scale = 100 µm; D. Smooth proximal tip of anisostyle, scale = 100 µm; E. Smooth distal tip of anisostyle, scale = 100 µm; F. Range of anisodiscorhabds, scale = 50 µm; G. Range of protorhabds from earliest to later stages showing gradual development of the three whorls, scale = 50 µm. All images taken from microscope slide of holotype.

FIGURE 13. Morphology, megascleres and microscleres of Latrunclava imago gen. et sp. nov.: A. Latrunclava imago gen. et sp. nov., preserved holotype RBCM 150 - 00490 - 001, central Aleutian Islands, 175 m, scale = 1 cm; B. Range of anisoconicorhabds, scale = 50 µm; C. Microfossil anisodiscorhabds of Latrunculia oamaruensis Hinde & Holmes, 1892 (from Hinde & Holmes, 1892: 218, Pl. 11, Fig. 34, 35), scale = 50 µm; D. Head of anisostyle, acanthose with retrovert spines, scale = 20 µm; E. Typical anisodiscorhabds with manubrium, scale = 20 µm; F. Anisodiscorhabd lacking a manubrium, scale = 20 µm; G. Protorhabds showing presence of budding manubrium, scale = 20 µm; H. Basal portion of anisodiscorhabd showing manubrium and basal whorl, scale = 20 µm; I. Apical whorl (apex absent), scale = 20 µm.