Leucandra serrata Azevedo & Klautau, 2007

Pereira, Sara Emilly, Azevedo, Fernanda, Hajdu, Eduardo, Cavalcanti, Fernanda F. & Klautau, Michelle, 2025, Calcareous sponges (Porifera, Calcarea) from São Sebastião, São Paulo: new species and new records in two marine protected areas of Southeastern Brazil Ecoregion, Zootaxa 5688 (1), pp. 1-107 : 61-65

Leucandra serrata Azevedo & Klautau, 2007

( Figs. 33–35 ; Table 14)

Synonyms: Leucandra serrata — Azevedo & Klautau 2007: 11; Muricy et al. 2008: 126; Lanna et al. 2009: 16; Ignacio et al. 2010: Table S1; Muricy et al. 2011: 29; Chagas & Cavalcanti 2017: 205; Oricchio et al. 2019: 887; Fonseca et al. 2023: 16.

Type locality: Bonfim Island , Angra dos Reis, Rio de Janeiro State, Brazil .

Material examined: MNRJ2979 , 2993 , between Ponta do Baleeiro and Saco Grande, São Sebastião Channel, São Sebastião, São Paulo State, Brazil, depth 4 m, coll. E. Hajdu, 09/I/2000 . MNRJ2997 , between Ponta do Baleeiro and Saco Grande, São Sebastião Channel, São Sebastião, São Paulo State, Brazil, depth 5 m, coll. E. Hajdu, 08/ I/2000 .

Comparative material examined: Type specimens of Leucandra serrata . Holotype —UFRJPOR4878, Bonfim Island , Angra dos Reis, Rio de Janeiro (-23.02333, -44.33166), depth 2 m, coll. M. Klautau, 05/IV/2003 . Paratypes —UFRJPOR4879 and 4881, Botinas Islands , Angra dos Reis, Rio de Janeiro (-23.05000, -44.32833), depth 2 m, coll. M. Klautau, 05/IV/2003 .

Colour: Beige in life and white in ethanol ( Fig. 33A–D ).

Morphology and anatomy: Massive sponges, with one to two apical oscula ornamented with a crown of trichoxeas ( Fig. 33A–C ). The surface is predominantly irregular, conulose, and hispid because diactines protrude through the cortex ( Fig. 33D ). However, in some regions of the body, the diactines are arranged tangentially to the surface, giving it a smooth appearance ( Fig. 33C , arrowhead). The atrial surface is hispid. Aquiferous system leuconoid.

The oscular crown of trichoxeas is supported by tetractines and rare triactines. The cortical skeleton is composed of triactines ( Fig. 34A, B ) and large diactines protruding singly or in tufts (with 2–6 spicules) through conules in the cortex ( Fig. 34C , arrowheads) or lying on the surface. Three jagged microdiactines were found only in one specimen (MNRJ2993), protruding through the cortex ( Fig. 34B ). Rarely, pseudosagittal triactines were found in the subcortical region ( Fig. 34D ). The choanosomal skeleton is disorganised, formed by triactines ( Fig. 34C ). The choanosomal canals are surrounded by tetractines ( Fig. 34E ). The atrial skeleton is composed of numerous tetractines and rare triactines ( Fig. 34F ). Fragments of trichoxeas were occasionally seen in the cortex and in the atrium.

Spicules ( Table 14):

Trichoxeas: Long, thin, cylindrical and sharp. Often broken. Size:>1,300.0/5.0 µm.

Diactines: Straight or slightly curved and fusiform, with both tips sharp ( Fig. 35A ). In the specimen MNRJ2993, some diactines presented the distal tip lanceolate. Size: 1,021.9 (±345.7)/33.8 (±11.9) µm.

Cortical microdiactines: Long, thin and sinuous, with a jagged distal tip and a smooth, thicker proximal tip ( Fig. 34B ). They are extremely rare or absent. Size: 442.5 (±67.2)/2.5 (±0.0) µm.

Cortical triactines: Slightly sagittal, variable in size, but most are as thin as the atrial ones. Actines are cylindrical to slightly conical, with sharp tips. The unpaired actine is straight and shorter than the paired ones, which are outwardly curved ( Fig. 35B ). Size: paired—256.8 (±58.2)/7.0 (±2.1) µm; unpaired—203.5 (±71.1)/7.1 (±2.5) µm.

Subcortical triactines: Pseudosagittal. Actines are conical to slightly conical, with sharp tips. Sometimes they are not typical pseudosagittals because the shorter paired actine is almost straight ( Fig. 35C ). Size: paired 1—247.5 (±71.8)/19.0 (±6.2) µm; paired 2—325.8 (±78.3)/18.0 (±5.9) µm; unpaired—186.5 (±55.1)/19.6 (±5.3) µm.

Choanosomal triactines: Large, variable in size, usually subregular, rarely regular. Actines are straight and conical to slightly conical, with sharp tips. The unpaired actine is often shorter than the paired ones ( Fig. 35D ). Size: paired—407.5 (±82.4)/28.3 (±9.5) µm; unpaired—301.5 (±68.3)/30.3 (±9.8) µm.

Tetractines of the canals: Slightly sagittal, with slightly conical and sharp basal actines. The unpaired actine is straight and a little shorter than the paired ones, which are curved ( Fig. 35E ). The apical actine is curved, smooth, conical and sharp. Size: paired—197.3 (±35.4)/9.9 (±1.6) µm; unpaired—186.5 (±66.2)/10.8 (±2.2) µm; apical— 70.0 (±17.8)/7.4 (±1.9) µm.

Atrial triactines and tetractines: Strongly sagittal. Basal actines are cylindrical, with sharp tips. The unpaired actine is straight and shorter than the paired ones, which are straight or slightly curved ( Fig. 35F, G ). The apical actine of the tetractines is conical, curved, smooth and sharp. Triactines size: paired—242.5 (±63.2)/6.3 (±1.3) µm; unpaired—185.3 (±75.6)/6.8 (±1.2) µm. Tetractines size: paired—265.5 (±47.0)/7.0 (±1.0) µm; unpaired—220.3 (±60.8)/7.5 (±0.8) µm; apical—64.0 (±12.0)/5.0 (±0.8) µm.

Ecology: All specimens were found exposed to high sedimentation ( Fig. 34A ), and one of them was partially covered by sediment. The same was observed in specimens from Rio Grande do Norte state by Lanna et al. (2009). Tubes of terebellid polychaetes were found on the external surface of our specimens ( Fig. 34A, C ), in addition to errant polychaetes and a small tanaid crustacean.

Geographic distribution: Northeastern Brazil ecoregion— Rio Grande do Norte State ( Muricy et al. 2008; Lanna et al. 2009), Brazil. Eastern Brazil ecoregion— Bahia State ( Chagas & Cavalcanti 2017; Fonseca et al. 2023), Brazil. Southeastern Brazil ecoregion—Angra dos Reis and Sepetiba Bay, Rio de Janeiro State ( Azevedo & Klautau 2007; Ignacio et al. 2010; Oricchio et al. 2019); São Sebastião Island (Ilhabela) and São Sebastião Channel (São Sebastião), São Paulo State ( Oricchio et al. 2019; present study), Brazil.

Remarks: Leucandra serrata was reported for the first time in São Sebastião Island by Oricchio et al. (2019), however, that study was not focused on sponges and no taxonomic description was provided then. Our specimens exhibit some differences from the original description of L. serrata , namely: i) diactines arranged in tufts protruding from conules on the surface, ii) diactines lying tangentially to the cortex in some regions, iii) a few lanceolate diactines (specimen MNRJ2993), iv) rare pseudosagittal subcortical triactines, and v) microdiactines that are very rare or even absent and longer [442.5 (±67.2)/2.5 (±0.0) µm] than those in the original description [111.0 (±17.9)/1.5 (±0.0) µm]. To address these potential differences, we examined the type material of L. serrata . We concluded that these features are variable within the species. For instance, although we did not observe diactines arranged in tufts in the type specimens, the paratype UFRJPOR4879 has a conulose surface, similar to our specimens. Additionally, in the holotype, some diactines are arranged tangentially to the surface and these spicules occasionally exhibit a lanceolate distal tip. Furthermore, subcortical pseudosagittal triactines, although rare, were found in all type specimens.

Regarding the jagged microdiactines, characteristic of L. serrata , they were rare in the holotype, occurring mainly near the oscular region, whereas in the paratype UFRJPOR4879, they were relatively common and variable in size. Beyond their variation in size and abundance, microdiactines also differ in shape, as they may be only slightly jagged or even smooth at the distal tip ( Azevedo & Klautau 2007; Fonseca et al. 2023; present study). This high variability suggests that microdiactines should not be considered diagnostic for L. serrata .

Figures

FIGURE 33. Leucandra serrata. A. Specimen MNRJ2993 in vivo. B. Preserved specimen MNRJ2993. C. Preserved specimen MNRJ2979, showing the oscular tube (arrow) and tangential diactines on the surface (arrowhead). D. Longitudinal view of the body wall and atrium, showing tufts of diactines protruding through conules on the surface and the openings of the exhalant canals in the atrial surface.

FIGURE 34. Leucandra serrata (MNRJ2979 and MNRJ2993). A. Tangential section of the cortex. B. Microdiactine in the cortex (arrowhead 1 points to the distal tip and arrowhead 2 points to the proximal tip), with detail of its jagged distal tip in the inset. C. Cross section of the body wall (arrowheads point to the conules with tufts of diactines). D. Subcortical triactines (arrowhead). E. Choanosomal canal. F. Tangential section of the atrium. All skeleton pictures were taken from the specimen MNRJ2979, except for B (taken from MNRJ2993). cx = cortex, at = atrium, c = choanosomal canal.

FIGURE 35. Leucandra serrata (MNRJ2979). A. Diactine. B. Cortical triactines. C. Subcortical triactines. D. Choanosomal triactines. E. Tetractine of the canals. F. Atrial triactine. G. Atrial tetractine.