Heteromeyenia insignis WELTNER (1895)

Tavares-Frigo, Maria da Conceição, Volkmer-Ribeiro, Cecília, Oliveira, Ana Elenice Zanini de & Machado, Vanessa de Souza, 2015, Freshwater sponges from the Pampa Biome, Brazil, with description of a new species of Oncosclera, Neotropical Biology and Conservation 10 (3), pp. 110-122 : 112

Heteromeyenia insignis WELTNER (1895)

( Figures 2A ; 3A )

Heteromeyenia insignis Weltner (1895, p. 142) ; Volkmer (1963, p. 277); Volkmer-Ribeiro et al. (2009, p. 100).

Examined material: BRAZIL, Rio Grande do Sul: Santana do Livramento, EPA of Ibirapuitã, Ibirapuitã River, Passo do Cerrito , 08.VI.2012, M.C. Tavares-Frigo and M. Pairet Jr. leg., MCN-POR 8927 ; 23.XI.2012, MCN-POR 8941; Arroio Sarandizinho, 02.XII.2011, M.C. Tavares-Frigo and M. Pairet Jr. leg., MCN-POR 8903; 30.III.2012, MCN-POR 8911; 08. VI.2012, MCN-POR 8933.

The sponge only occurred in two stations ( Table 1), on clean rocky substrates or with accumulated fine sediments, in areas exposed to sunlight and with reduced water coverage. In Passo do Cerrito, St. 2, in June 2012, at the time of sampling, the surface of the river was frozen. The sponge formed seasonal crusts, gemmuliferous, shallow and delicate or with finger-like projections, light green in colour ( Figure 2A ). The spicule set ( Figure 3A ) corresponded to that shown in the re-description of this species (Volkmer, l963).

Remarks: To date, records of H. insignis are circumscribed to the states of Rio Grande do Sul and Santa Cata- rina ( Weltner, 1895; De Rosa-Barbosa, 1984; Volkmer-Ribeiro et al., 2009), occurring in locations exposed to the sun, commonly in rivers with cold, shallow and rapid waters, flowing over basaltic bedrock of the southeastern flank, while rarely encrusting submerged vegetation, and if so, with very thin specimens. Due to their soft consistency, these sponges disintegrate during winter/torrential waters distributing their abundant gemmules downstream, where they become trapped in the rocky interstices, devel- oping again in the spring, as shown in Table 1. The species is included in the Rio Grande do Sul State’s official list of threatened fauna (Rio Grande do Sul, 2014).

Figures

Figure 2. Photographs of the living sponge species detected in the Environmental Protection Area (EPA) of Ibirapuitã, southern Brazil. A, Heteromeyenia insignis WELTNER (1895); B, Corvospongilla seckti BONETTO and EZCURRA DE DRAGO (1966); C, Corvoheteromeyenia australis (BONETTO and EZCURRA DE DRAGO, 1966); D, Oncosclera navicella (CARTER, 1881); E, Oncosclera schubarti (BONETTO and EZCURRA DE DRAGO, 1967); F, Oncosclera rosariae n.sp. Bar = 3 cm.

Figure 3. Camera lucida drawings of the spicular sets of sponge species sampled in the Environmental Protection Area (EPA) of Ibirapuitã, southern Brazil. A, Heteromeyenia insignis WELTNER (1895); B, Corvospongilla seckti BONETTO AND EZCURRA DE DRAGO (1966); C, Corvoheteromeyenia australis (BONETTO AND EZCURRA DE DRAGO, 1966); D, Oncosclera navicella (CARTER, 1881); E, Oncosclera schubarti (BONETTO AND EZCURRA DE DRAGO, 1967); F, Oncosclera rosariae n.sp. meg: megascleres; gem: gemmoscleres; gem-1: short gemmoscleres; gem-2: long gemmoscleres; mic: microscleres; mic-1: chaela microsclere; mic- 2: birotulated microsclere). Bar = 50 micrometers.