Ephydatia caatingae, Nicacio, Gilberto & Pinheiro, Ulisses, 2015

Nicacio, Gilberto & Pinheiro, Ulisses, 2015, Biodiversity of freshwater sponges (Porifera: Spongillina) from northeast Brazil: new species and notes on systematics, Zootaxa 3981 (2), pp. 220-240 : 227-230

Ephydatia caatingae sp. nov.

( Figures 6 and 7 , Table 1 )

Material studied. Holotype: Poço Verde Pond, Orobó, Pernambuco, Brazil, 7°44'10.7"S 35°32'35.8"W, UFPEPOR1733, coll. U. Pinheiro, 17.ix.2013. Paratype: Poço Verde Pond, Orobó, Pernambuco, Brazil, 7°44'10.7"S 35°32'35.8"W, UFPEPOR1736, coll. U. Pinheiro, 17.ix.2013. Comparative material: Ipanema River, Santana do Ipanema, Alagoas, Brazil, 9º21'52.8''S 37º15'28.4''W, UFPEPOR1402, coll. G. Nicacio, 15.xii2012. Poço Verde Pond, Orobó, Pernambuco, Brazil, 7°44'10.7"S 35°32'35.8"W, UFPEPOR1403, 1404, coll. L. R. C. Lima, 29.ix.2012; UFPEPOR 1737, 1740, 1742, 1744, coll. U. Pinheiro, 17.ix.2013.

Etymology. The epithet is related to the type locality, Caatinga Brazilian biome, where specimens were found.

Diagnosis. Ephydatia species characterized by birotules as gemmuloscleres with strongly incised rotules and smooth or spined shaft, with secondary spines.

Type locality. Brazil, Pernambuco, Orobó, Poço Verde Pond (7°44'10.7"S 35°32'35.8"W).

Holotype UFPEPOR1733. General morphology. Encrusting sponge with reticulated surface. Measuring 1cm in thickness and 12cm in diameter. Green colour ( Fig. 6 a). Consistency of live sponge is fragile and brittle, paucispicular skeleton, spongin abundant. Spicules. Megascleres spined or smooth oxeas (267–302.2 –332/10– 14.4–17µm), slender and slightly curved ( Fig. 7 a). Microscleres absent. Gemmuloscleres birotules (32–40–48/5- 7.1-8/15-21.3–25 µm), smooth or spined shaft, with secondary spines (spines ornamented by microspines). The rotules are strongly incised ( Fig. 7 b). Gemmules scattered, hemispherical, averaging 275-351-387µm in diameter. Gemmular theca tri-layered with well-developed pneumatic layer of irregular spongin chambers and gemmuloscleres are radially embedded in the outer and pneumatic layers ( Fig. 7 c,d).

Comparative material. General morphology. Encrusting sponge with 1cm thickness and averaging 20cm in diameter. The colour is green when the sponges are exposed to sunlight and beige in sciaphilous habitats ( Fig. 6 b). Spicules are of the same morphology as described in the holotype. Megascleres (250–307.8 –362/9–13.9–18µm), Microscleres absent. Gemmuloscleres (32–43.8–55/5-7.5-10/15-22.5–26 µm). Gemmules averaging 262-343- 450µm in diameter.

Distribution and ecological notes. The new species is so far recorded from Pernambuco and Alagoas states of Brasil. The region where this species was found is characterized by environments with low rainfall and a semi-arid climate. Specimens were collected on rocky substrate and tree trunks in shallow water. Gemmules were often abundant. Green specimens in symbiosis with algae were found living exposed to sunlight.

Remarks. The cosmopolitan genus Ephydatia is widely distributed throughout the Northern Hemisphere, but it is also has scattered records from Southern Hemisphere ( Manconi and Pronzato 2007). This supposed wide distribution might be due to the existence of a species-complex suggested for widespread species. From the Neotropical Region there is only one record so far, viz. Ephydatia facunda Weltner, 1895 . This species has a supposed widespread distribution from the Caribbean to southern Brazil.

Manconi & Pronzato (2005) recorded E. facunda from Cuba and expanded its distribution in South America, previously only known from Brazil. However, the specimens from Cuba have remarkable morphological divergences compared to the Brazilian specimens ( De Rosa-Barbosa 1984, Volkmer-Ribeiro et al. 1988, Volkmer- Ribeiro & Tavares 1990, Pinheiro et al. 2004, Volkmer-Ribeiro & Machado 2007).

Ephydatia facunda from Cuba is characterized by having minute gemmules and gemmuloscleres smaller than those of the Brazilian specimens ( Tab. 1 ). The main morphological divergence among descriptions of these disjunct populations concerns the remarkable differences of gemmulosclere shape with thin smooth shaft. In fact, notable differences between specimens of E. facunda and their widespread distribution suggest the existence of a speciescomplex.

The specimens studied here exhibit morphological differences from the other South American Ephydatia species that justify the proposal of a new species. Compared to Ephydatia facunda , the closest species geographically, it presents a different morphology of the birotule gemmuloscleres. Ephydatia facunda has shallowly incised rotules with the spines on the shaft being simple and sharp, compared to the strongly incised rotules and composite spines in Ephydatia caatingae sp. nov. Additionally, in gemmules, the gemmuloscleres are more densely distributed in Ephydatia facunda than in Ephydatia caatingae sp. nov. ( Fig. 7 c,d). Despite the fact that fossil species, Ephydatia chileana Pisera & Sáez, 2003 shared incised rotules with Ephydatia caatingae sp. nov., its spines of the shaft are simple against the composite spines of the new species.

Five species of Ephydatia are known from North America: E. fluviatilis (Linnaeus, 1758) , E. millsii ( Potts, 1887) , E. mulleri (Lieberkühn, 1855) , E. robusta ( Potts, 1887) , and E. subtilis Weltner, 1895 . Among these species, only E. robusta has spines on the shaft of birotules, thus being the closest species to Ephydatia caatingae sp. nov.; however, the spines of the shaft are simple against the composite spines of the new species.

Species/ Specimens Locality Megasclere Gemmulosclere (*)Values are in µm and expressed as shortest length–mean length–longer length/thinner thickness–mean thickness–widest thickness. where appropriate; (1) Weltner (1895); (2) Gee (1930); (3) De Rosa-Barbosa (1979); (4) Penney & Racek (1968); (5) Pinheiro et al (2004); (6) Manconi & Pronzato (2005); (7) Pisera & Saez (2003); (8) Present Work.

Poirrier (1974) experimented with Ephydatia fluviatilis in different enviromental conditions and proposed that this species had a huge ecomorphic variation related to the prevailing habitat. At that time, he proposed E. robusta as synonym of Ephydatia fluviatilis and suggested this species was truly cosmopolitan, drawing attention to the true geographic variation which is usually masked by the high adaptive ecomorphic variation exhibited in its spicules. On the other hand, this recommendation is not being followed, because Poirrier (1982) and van Soest et al. (2015) have considered E. robusta as valid species. It is possible that some species may have an ecomorphic variation that makes it difficult to take a taxonomic decision. However, we can not generalize this feature for all freshwater sponge species that have alleged widespread distributions. Taxonomic works (revisions) and taxonomists of freshwater sponges are scarce, both of which are necessary to solve this problem. For example, Pinheiro (2007) verified that only three species (6%) of freshwater sponges recorded from Brazil are not endemic to South America ( Tubella pennsylvanica (Potts, 1882) , Eunapius fragilis ( Leidy, 1851) and Heteromeyenia stepanowii (Dybowski, 1884)) , but all of these have few and simple spicules and have not been revised. This low number suggests that species identified as allegedly widespread might be directly related to the paucity of morphological distinctness of characters under study. There is still a difficulty in recognizing species complex and it is possible that certain species can lead to misinterpretation of alleged cosmopolitanism. New experimental works are necessary to find any real clear-cut distinction between ecomorphic variation and speciation in such sponges.

Figures

FIGURE 6. Ephydatia caatingae sp. nov. Specimens in situ: (a) UFPEPOR 1733 (Holotype); (b) UFPEPOR 1736 (Paratype). Scale bars: 1 cm.

FIGURE 7. Ephydatia caatingae sp. nov.: (a) megascleres; (b) gemmuloscleres; (c, d) gemmules. Scale bars: a— 100 µm; b— 10 µm; c— 100 µm; d— 50 µm

Tables

TABLE 1. Spicule micrometries of Ephydatia from the Neotropical Region.

	Oxea	Birotule	Gemmule
Holotype E. facunda	Brazil (RS)1 250-300–360/ 8–10	36–44–52/4–5// 24–28
Holotype E. facunda	Brazil (RS) 2 323–374	34–50
Holotype E. facunda	Brazil (RS) 3 210–356–465/ 9–15–22	48–58–99/7–10–14// 22–27–30
E. facunda	Brazil (RS); 250–370/9–12 Argentina 4	35–45–52/4–5// 23–27	410–480
E. facunda	Brazil (AL) 5 262–318–470/ 7–12.3–18	47–53–62/5–5.5–8// 17–23–27	388–442
Ephydatia sp.	Cuba6 232–316/7–14	23–51/4–7//19–25	185–278
Ephydatia fluviatilis	USA 210–400/6–19	26–30//18–21	350–450
Ephydatia subtilis	USA 158/2,6	23/1,7//9,5	176
Ephydatia robusta	USA, Mexico 230–330/12–17	45–50/6–7//20–22	360–400
Ephydatia millsii	USA 180–270/9–12	36–48//23–28	300–360
Ephydatia mulleri	USA, Europe, Asia 200–350/9–20	12–20/4–6//20–25	350–450
Ephydatia chileana	Chile7 240–350	39–45/5.5–7.2//24.8–27	237–250
E. caatingae sp. nov. Holotype UFPEPOR 1733	Brazil (PE) 8 267–302.3–332/ 10–14.4–18	32–40.0–48/5–7.1–8// 15–21.3–25	275–387
E. caatingae sp. nov. Paratype UFPEPOR 1736	Brazil (PE) 8 257–300.9–322/ 9–13.0–16	42–48.3–55/6–7.2–8// 19–22.9–26	262–450
E. caatingae sp. nov. UFPEPOR 1402	Brazil (AL) 8 250–320.3–362/ 9–14.3–17	32–43.1–54/6–8.1–10// 19–23.2–26	-