Thoosa mismalolli Carballo, Cruz Barraza & Gómez, 2004

Pacheco, Cristian, Carballo, José Luis, Cortés, Jorge, Segovia, Johanna & Trejo, Alejandra, 2018, Excavating sponges from the Pacific of Central America, descriptions and a faunistic record, Zootaxa 4370 (5), pp. 451-491 : 481-482

Thoosa mismalolli Carballo, Cruz Barraza & Gómez, 2004

Material examined. MZUCR.182: Isla del Caño , 4 m, 1984, coll. Jorge Cortés Núñez, det. Cristian Pacheco Solano . MZUCR.380: Isla del Caño , 10 m, 12. II.2011, coll. and det. Cristian Pacheco Solano .

External morphology. Endolithic sponge in alpha morphology. Material not sufficient to allow reliable description of external characters.

Excavation. Fused galleries with average diameter of 2 mm. Erosion scars with diameters between 29 and 56 µm. Inner surface of scars irregular, with pronounced ridges and radial structures ( Fig. 34 ), providing additional information to distinguish between Thoosa and Cliona ( Calcinai et al. 2004) .

Spicules. Megascleres tylostyles and oxeas, microscleres oxyaster derivates and amphiasters ( Fig. 35 ). Tylostyles scarce, not measured. Oxeas centrotylote, with length average of 57.4 µm (σ=7.7). Thick amphiasters with 14 nodules, 2 at each apex and 6 per verticil, in alternating arrangement. Nodules microspined. Nodulose amphiaster average dimensions of 21,3 µm (σ=2.3) x 14,1 µm (σ=2.4). Thinner amphiasters with fourteen nodules in arrangement as described above, irregular endings or smooth, with average dimensions of 17,1 (σ=3.0) x 10,2 µm (σ=2.4). Biradiate, triradiate or tetraradiate oxyasters, some with microspination, length average of 50,5 µm (σ=7.2).

Ecology. The specimens were found in dead pocilloporid corals at 10 m depth.

Distribution and previous records. The species was described from Mexico ( Carballo et al. 2004), and Guzmán (1988) probably from Costa Rica (see Remarks), which our study confirmed ( Fig. 36 ). Todate Costa Rica was the only site in Central America where this species was detected.

Remarks. The three Thoosa species presently known in the ETP— T. calpulli , T. mismalolli and Thoose purpurea Cruz-Barraza et al., 2011 —are quite easy to distinguish by comparing the most common spicule, the main amphiaster ( Fig. 31 , 35 and Fig. 9A in Cruz-Barraza et al. 2011). However, all three species were only recently described and any findings before 2004 relied on the then existing literature. Guzmán (1988) sampled a Thoosa species from Costa Rica and identified it as Thoosa mollis Volz 1939 . However, the distribution of this species is restricted to the Adriatic Sea in the Eastern Mediterranean ( Soest et al. 2016). In this study, we found two species of this genus, T. mismalolli and T. calpulli in Costa Rica. Guzmán’s material was very likely T. mismalolli , as the spicules of T. mollis and T. mismalolli are similar.

Figures

FIGURE 9. Spicules of Cliona euryphylle: A) tylostyles, with one short derivate, B) morphologic variation of heads of tylostyles, C) morphologic variations of spirasters.

FIGURE 31. Spicules of Thoosa calpulli: A) symmetric amphiasters, B) reduced oxyasters, with the upper one in the “birdwing” form, C) asymmetric amphiasters.

FIGURE 34.Thoosa mismalolli bioerosion.A) Erosion chamber (arrow) and B) erosion scars.

FIGURE 35. Spicules of Thoosa mismalolli: A) centrotylote oxea or straight biradiate oxyaster, biradiate oxyaster in “bird wing” form, triradiateand quintaradiate oxyasters,the latter microspined, B) thick and slim nodulose and reduced amphiasters, and larger smoothand hastate-rayed amphiaster.

FIGURE 36.Distribution of Thoosa mismalolli in the study area.