Heteromeyenia insignis Weltner 1895

Heteromeyenia insignis Weltner, 1895 Synonymy. For synonymy see Muricy et al. (2011). Type Material: Holotype. ZMB Por 2148 (not seen). Museum für Naturkunde, Berlin. Material studied. MNRJ 0 0 0 2, Atlântico Sul Basin, Rio Grande do Sul State, Brazil. Diagnosis. Species of Heteromeyenia characterized by the presence of acanthoxea megascleres with tuberculated spines and acanthoxea microscleres; two categories of gemmuloscleres: birotules with microspined margins of rotules and spined shaft, and pseudobirotules with large apical spines disposed orthogonally to the shaft, with sharp terminations bent as a hawk’s bill, and spined shaft. Description. Sponge encrusting. Surface hispid with protuberances. Oscules irregularly scattered over the surface of the sponge. Colour is bright green in vivo and creamy white when dry (Fig 4). Consistency soft and gelatinous in life, fragile in the dry condition. According to Volkmer-Ribeiro (1963) the species can be confused with algae when touched. Ectosomal skeleton with scattered microscleres. Choanosomal skeleton is an irregular network of paucispicular parallel fibres. Megascleres and microscleres are isolated and scattered randomly. Megascleres acanthoxeas (190–261–303 / 12–15 µm) with tuberculated microspines, straight or slightly curved, sharpening gradually towards the apices (Fig. 5 a,b). Microscleres acanthoxeas (35–60–75 / 3–5 µm) with straight or curved, simple or compound spines. Curved spines occur near the tips of the spicule, with centripetal direction and are always simple. Straight spines occur in the median portion of the spicule, can be simple (rare) or compound (predominant). The compound spines have a bouquet-like structure, where the primary spine supports the secondary spines (Fig. 5 c,d). Gemmuloscleres in two categories: pseudobirotules (fig. 5e) (85–105–125 / 5–8 // 15–25 µm) and birotules (fig. 5f) (73–81–105 / 5–8 // 10–18 µm), in both the shaft present numerous conical spines (Fig. 5 e,f). Pseudobirotules with large apical spines (pseudorotules) disposed orthogonally to the shaft, with sharp terminations bent as a hawk’s bill. The teeth project from the center of the pseudorotule and can be simple or anastomosing (Fig. 5 g). Birotules with smooth surface rotules, flattened discs with marginal microspines bent towards the other rotule (Fig. 5 h). Both are found in similar proportions in the gemmules. Gemmules (450–500 µm) abundant, isolated or in groups, scattered throughout the sponge body, spherical, with the side of the foramen variously flattened (Fig. 6 a). Foramen with irregular shape. Gemmular theca tri-layered with gemmuloscleres radially embedded. Pneumatic layer well developed (Fig. 6 b,c). Ecology. The specimen was found encrusting small submerged pebbles. Distribution. Brazil: Santa Catarina and Rio Grande do Sul States: South Atlantic Basin. Remarks. Weltner (1895) described H. insignis based on material collected by Fritz Müller from Blumenau (Santa Catarina State). Probably, this specimen was collected in the Itaja River, since all the sponges deposited in the collection of Museu de Zoologia of Universidade de São Paulo (MZUSP), that were collected by Fritz Müller, had been recorded from this locality. Volkmer-Ribeiro (1963) redescribed the species based on material collected at Dom Pedro I stream, in São Francisco de Paula (Rio Grande do Sul State), to complete the extremely succinct description offered by Weltner (1895). Her material was deposited at Museu Nacional (MNRJ 0002), and is reexamined here. Ezcurra de Drago (1979) proposed the synonymization of H. insignis and H. baileyi, arguing that the material used for redescription of the former (MNRJ 0002) also has hook-like spines in the rotules, a trait considered by Volkmer-Ribeiro (1963) as a distinctive character between both species. This synonymy was completely ignored in subsequent works of other authors (De Rosa-Barbosa 1984; Volkmer-Ribeiro et al. 1988; Batista et al. 2007). Kilian & Wintermann-Kilian (1976) described Heteromeyenia horsti from material collected in Chile. Comparison of the description and images available of this species (Kilian & Wintermann-Kilian 1976; Ezcurra de Drago 1979) with H. insignis does not reveal any significant differences. The size and morphology of the spicules are identical. It is possible that both species are synonymous, but to confirm this hypothesis it is necessary to analyze the type material of H. horsti, which was not possible at this moment. This is the first work providing scanning electron micrographs of the complete set of spicules of Heteromeyenia insignis. Ezcurra de Drago (1979) offered images of the gemmuloscleres only. When we compare H. insignis (MNRJ 0002) and the redescription of the lectotype of H. baileyi (see Manconi & Pronzato 2002; Fig. 38), reveals characteristics that justify H. insignis as a valid species. In H. baileyi the shaft of gemmuloscleres can be smooth or with a few spines (see Manconi & Pronzato 2002; Fig. 38i,j), while H. insignis has the shaft completely covered by spines (Fig. 5 e,f). The teeth of pseudorotules in H. baileyi have tips bent backwards (180 angle, Manconi & Pronzato 2002; Fig. 38k), whereas in H. insignis, this bending is more discreet, with tips resembling a hawk’s bill, pointing towards the other pseudorotule (90 angle, Fig. 5 g). Another character that could be useful to distinguish species of Heteromeyenia is the morphology of microscleres. However, there is no SEM done of the type material of H. baileyi, which precluded this comparison. Furthermore, previous studies on Heteromeyenia did not discuss this character. Finally, both species have a remarkably disjunct distribution: Heteromeyenia baileyi is known from the Northern Hemisphere in Nearctic and Palearctic (US, Canada, Germany, Portugal, Spain, and Poland) and H. insignis only from Neotropical Region (Brazil, and Argentina).

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