Skeletons in confusion: a review of astrophorid sponges with (dicho-) calthrops as structural megascleres (Porifera, Demospongiae, Astrophorida) Author Van Soest, Rob W. M. Author Beglinger, Elly J. Author De Voogd, Nicole J. text ZooKeys 2010 68 1 88 http://dx.doi.org/10.3897/zookeys.68.729 journal article http://dx.doi.org/10.3897/zookeys.68.729 1313-2970-68-1 Calthropella Calthropella pathologica (Schmidt, 1868) Figs 26 A-F Stelletta pathologica Schmidt 1868 : 19, pl. III figs 3-4. Calthropella pathologica ; Topsent 1938 : 24; Vacelet 1969 : 166, fig. 3; Pouliquen 1972 : 746, pl. 7 fig. 3; Maldonado 1992 : table 1. Pachastrissa pathologica ; Voultsiadou and Vafidis 2004 : 593. Material examined. Lectotype (designation herein), MNHN DT 753, Coast of Algiers, Expedition Scientifique de l'Algerie , nr. 66, 1842. Paralectotype MNHN DT 754, from same locality. Redescription (partly from Topsent, 1938). Two specimens are present in the Schmidt collection of the Museum National d'Histoire Naturelle, Paris, the largest (MNHN DT 753) of which is 4.5 cm in widest size and 2-2.5 cm high, here chosen as the lectotype. The smaller specimen (MNHN DT 754), here designated paralectotype, size 1 x 3 cm (now apparently reduced to 1 x 1.5 cm) was examined by us and we made SEM photos of the spicules. Both specimens have a rough surface (Fig. 26A). According to Vaclelet (1969) living specimens are white, but the type specimens we examined were yellowish in alcohol. Spicules: Calthrops, tuberculated spherasters, oxyasters. Calthrops (Figs 26 B-C ): According to Topsent the skeleton includes calthrops with cladi up to 550 x 75 µm (but widely different sizes are present, including 'microcalthropes' ). We measured a size range of the cladi of 32-366 x 5-72 µm (cladomes 48-480 µm ) but no clear separation in smaller and larger size categories was apparent. The shapes of the calthrops was very variable with many 'short-shafted triaenes' , mesotriaene modifications, curved and stunted cladi. No dichocalthrops are reported from this species. The megasclere complement also comprised thin oxeas of 15 µm thickness (Fig. 26B). Cross sections of the type specimens examined by P. Cardenas show scattered bundles of the thin oxeas running vertically to the surface, but their length still is difficult to determine. We are indebted to P. Cardenas for this information. The largest unbroken piece we found in preparations of DT 754 was 2000 x 12 µm , which is in accordance with findings of Voultsiadou and Vafidis (2004) . Asters (Figs 26 D-F ) occurred in three distinct categories: thick-centred with spined-tuberculated rays, asters with thick pointed rays lighly spined, and small smooth oxyasters. Lightly spined oxyasters (Fig. 26E) with swollen pointed rays, often with bifid rays, not very common, diameter 23 -24.9- 27 µm . Small, smooth oxyasters (Fig. 26F), often slightly irregular in ray length, diameter 9 -10.2- 12 µm . Tuberculated asters with ornamented rays (Fig. 26D); compared to Calthropella (Calthropella) geodioides the rays were relatively long; sizes highly variable, but overlapping without clear separation in smaller and larger asters, diameter 9 -18.4- 24 µm Figure 26. Calthropella (Calthropella) pathologica , lectotype MNHN DT 753 and paralectotype MNHN DT 754, from Algiers, A habit of lectotype (grid is 1 cm) B-F SEM images made from the paralectotype, B overview of spicules C various calthrops including a pentactinal modification D tuberculated spheraster E large irregular oxyspheraster F small oxyaster. Habitat. Deep water, and in caves in more shallow water, depth occurrence at least 13-250 m. Vacelet (1969) reported that his specimen was insinuating in calcareous algae. Distribution. Off the coast of Algeria, no further data; Cassidaigne, Marseille region; Sicily-Tunis region; Alboran Sea, 39°N -3°W; Rhodos, Aegean Sea, 36°N; 28°E. Remarks. Topsent (1938) remarked that the specimens are similar in most aspects to Calthropella geodioides but differ in the tendency of the calthrops to develop extra cladi . In addition the tuberculated asters of that species have shorter rays (almost entirely consisting of tubercles). Oxeas are stated in Voultsiadou and Vafidis (2004) to be all broken, whereas Vacelet (1969) notes 'wide axial canals' , adding to the conclusion that they are not of structural significance. Nevertheless, the bundles reported by P. Cardenas (in litteris) appear to indicate these oxeas are proper to the sponge. Possibly, they are a remnant of ancestral radiating oxeas.