Platydoris guarani sp. n.

Lima, Patricia O. V. & Simone, Luiz Ricardo L., 2018, Revision of Platydoris angustipes and description of a new species of Platydoris (Gastropoda: Nudibranchia) from southeastern Brazil based on comparative morphology, Zoosystematics and Evolution 94 (1), pp. 1-15 : 3-4

Platydoris guarani sp. n. Figures 7 , 8 , 9 , 10 , 11

Platydoris angustipes Er. Marcus, 1957: 422, fig. 81-89; Ev. Marcus 1972: 79; García et al. 2002: 53, fig.2K; García et al. 2008: 148; Alvim and Pimenta 2013: 186, figs. 2C; 21-22; Padula et al. 2012: 3 (non Mörch 1863).

Type material.

Holotype: BRAZIL, Rio de Janeiro, Ilha Grande, Angra dos Reis, MZSP 86082, 1 specimen (E.P. Gonçalves, L.R. Simone & P. Oristanio, coll., 24/ix/2006, 17m depth, Ponto 3, Pinguino Wreck). Paratype: BRAZIL, Rio de Janeiro, Ilha Grande, Angra dos Reis, MZSP 134877, 2 specimens (E.P. Gonçalves, L.R. Simone & P. Oristanio, coll., 24/ix/2006, 17m depth, Ponto 3, Pinguino Wreck).

Type locality.

Brazil, Rio de Janeiro state, Angra dos Reis.

Etymology.

The specific epithet is a noun in apposition, derived from the native Guarani indigenous people, some tribes of which still reside in Rio de Janeiro.

Diagnosis.

Body of orange color, with a white ribbon on its edge and brown spots just above the ribbon (they can be seen both dorsally and ventrally). Radula with outermost teeth not spatulate, with apex hook-shaped; cusp simple and smooth. Presence of m4a and m7b odontophore muscles. Gonad readily visible. Absence of spines on internal surface of penis and vagina.

Description.

External morphology (Figure 7A-C ): Size ~60 mm length, ~40 mm width. Body color orange with white ribbon on its edge and brown spots just above the ribbon that can be seen both dorsally and ventrally (Fig. 7A-B ). Body flattened and wide with small tubercles around dorsum. Rhinophores with ~25 transversal lamellae, very thin; color dark orange; rhinophoral sheaths with very small lobes (Fig. 7C ). Gill composed of six white tripinnate branched branchial leaves, arranged in circular fashion surrounding anus; branchial sheaths also with very small tubercles (Fig. 7C ). Mouth opens in anterior ventral region, between anterior region of notum and foot. Digitiform tentacles present. Anterior border of foot bilabiate and longitudinally notched.

Haemocoel organs: Of similar proportions as P. angustipes (see above).

Circulatory and excretory systems (Figure 8A, B ): Same as P. angustipes , but with renal vesicle very large, well-developed, of about same length and width as ventricle (Fig. 8B ), extending from dorsal to medial sinus, anteriorly connected to renal vesicle, extending posteriorly to center of gill circle and opening in nephrostome (Fig. 8A ). Nephrostome pore not readily apparent.

Digestive system (Figures 8C, D ; 9A-D ; 11A-C ): Same pattern as P. angustipes , but with the following differences: m2, twice as long, not bifurcated on insertion (Fig. 9A, B ); m4a, pair of thin muscles originating in posterior region of m4 and inserting in the middle of odontophore cartilages, dorsally connected to m7b (Fig. 9D ); m7b, pair of thin and short muscles originating in posterior region of m6, with joint insertion with posterior part of m7 (Fig. 9C, D ). Radular sac ~1/5 as large as odontophore (Fig. 9A, B ). Radular teeth (Fig. 11A-C ): anterior region broader than in P. angustipes ; rachidian teeth also absent; formula 35 x 60.0.60 (in 60 mm long specimen, MZSP86082). Each lateral tooth with broad base, tapering towards apex, hook-shaped, with single terminal cusp; outermost teeth narrower than in P. angustipes , inner base width ~1/2 lateral teeth width, apex also hook-shaped, cusp simple and smooth (Fig. 11C ). Pair of salivary glands long, tubular, bulging in anterior portion and tapering posteriorly; duct inserting in anterior region of esophagus, extending posteriorly to ventral middle region of digestive gland (Fig. 8D ). Esophagus simple, originating dorsally to odontophore, inserting directly in anterior region of stomach; longitudinal folds on inner surface with same diameter along esophagus’ entire length. Stomach oval, with folds on the center of entire inner surface (Fig. 8C ). Common opening for esophagus, stomach and caecum located on digestive gland. Intestine with longitudinal folds along its entire length; diameter similar to that of esophagus; anterior portion S-shaped, about twice longer than in P. angustipes (Fig. 8C ). Caecum: short elongated sac, located ventrally to stomach, opening in anterior portion of stomach close to esophageal insertion; ~1/12 length and ~1/5 width of stomach (Fig. 8C ). Digestive gland dark beige; largest organ of visceral mass; cone-shaped, anterior portion about twice as wide as posterior portion; inner surface of gland sponge-like, bearing distinct main duct. Anus opening into anal papilla on the center of gill circle, similar to P. angustipes .

Genital system (Figure 10A-B ): Located between buccal mass and digestive gland, longitudinal on right side of animal. Genital opening on right side, on anterior third of animal, located between foot and notum. Gonad circling around all digestive gland, but easy to distinguish, unlike in P. angustipes . Hermaphrodite duct thin, long. Ampulla located on female gland, elongated and tubular. Prostate rounded, glandular, of same length as ampulla (Fig. 10A ). Vas deferens about same length as ampulla Penis muscular, cylindrical and very broad, ~1/2 length and three times wider than ampulla, without spines (Fig. 10A ). Female gland well-developed, rounded, occupying ~20% of reproductive system volume; divided into mucus gland (~2/3 of female gland, color beige) and albumen gland (~1/3 of anteriormost region, dilated, irregularly shaped, color dark brown). Oviduct occupying ~1/5 of female gland volume (Fig. 10A ). Uterine duct thin, relatively short, length ~1/10 of vagina length, located on the base of seminal receptacle, inserted in female gland near oviduct (Fig. 10B ). Seminal receptacle elongate, as long as bursa copulatrix and ~1/3 its width; connected to vagina through stalk with same length and ~1/2 width of vagina (Fig. 10B ). Bursa copulatrix rounded, ~1/2 length of vagina, connected to vagina posteriorly to seminal receptacle (Fig. 10B ). Vagina cylindrical, very broad, with wide and thick folds, without spines; approximately as long and as wide as penis; positioned dorsally in relation to prostate and parallel to penis in genital opening (Fig. 10B ).

Nervous system (Figure): Same as in P. angustipes .

Distribution.

Brazil ( Valdés et al. 2006). Pernambuco: Fernando de Noronha ( García et al. 2002); Alagoas: Saco da Pedra ( Padula et al. 2012); Bahia: Praia de Itapoã ( García et al. 2008); Rio de Janeiro: Cabo Frio: Ilha Comprida; Arraial do Cabo: Prainha (Alvim and Pimenta 2014).

Habitat.

Under stones, associated with sponges and ascidians ( García et al. 2002), from 0 to 17 m depth.

Material examined.

Types. Additional material: BRAZIL, Rio de Janeiro, Enseada da Meia Lua, Cabo Frio, MZSP 97625, 1 specimens (V. Padula, coll., 23/iv/2010); Ilha dos Papagaios , MZSP 97515, 1 specimen (V. Padul, coll., 17/x/2009) .

Figures

Figure 7. Platydoris guarani, living animals. A. Dorsal view, specimen from Papagaio, Cabo Frio, Rio de Janeiro (MZSP 97331). B. Same, ventral view. C. Living animal with spawning, specimen from Enseada da Meia Lua, Cabo Frio, Rio de Janeiro (MZSP 97625). All photograph by V. Padula.

Figure 8. Platydoris guarani. A circulatory and excretory system, ventral view B renal vesicle C medium digestive system, dorsal view D detail of salivar glands. Scale bars: 2 mm (A, B, D); 5 mm (C).

Figure 9. Platydoris guarani. Odontophore. A dorsal view with radula B same, ventral view C same, dorsal view with removed radula D same, dorsal view, with folded down muscles. Scale bars: 2 mm.

Figure 10. Platydoris guarani. Reproductive system A general ventral view B detail of Bursa copulatrix, seminal receptacle, uterine duct and vagina. Scale bars: 2 mm.

Figure 11. SEM of radula of Platydoris guarani. A panoramic view B central region with rachidian tooth absent C lateral teeth. Scale bars: 300 µm (A); 100 µm (B); 30 µm (C).