Jorunna spongiosa, Alvim, Juliana & Pimenta, Alexandre Dias, 2013

Alvim, Juliana & Pimenta, Alexandre Dias, 2013, Taxonomic review of the family Discodorididae (Mollusca: Gastropoda: Nudibranchia) from Brazil, with descriptions of two new species, Zootaxa 3745 (2), pp. 152-198 : 182-185

Jorunna spongiosa sp. nov.

( Figures 2A–B ; 19–20)

Type material. Holotype: MNRJ 13781, 24 /v/2009, 14.0 mm long alive, 2 m depth, J. Alvim coll. [dissected]; Paratypes (all from type locality): MNRJ 14971, 22 /viii/ 2009, 1m depth, J. Alvim coll. [2; two dissected]; MNRJ 13203, 06 /xi/2006, P.M.S. Costa coll. [2; two dissected]; MNRJ 13197, 01 /ix/2008, J. Bahia coll. [1]; MNRJ 13996, 08 /vii/2009, J. Alvim coll. [1]; MNRJ30823, 24 /v/2009, J. Alvim coll. [1].

Type locality. Canal de Itajurú (22°53’13.73”S; 42°00’60”W), Cabo Frio, Rio de Janeiro state, Brazil.

Etymology. “ spongiosa ” in Latin means “having the texture of the sponges”. It is referring to the mantle appearance due to the presence of the caryophyllidia which makes the specimen almost invisible on the sponge that it preys ( Fig. 20 D).

Diagnosis. Dorsal color whitish gray to white, with several rounded blotches darker than the rest of the mantle; eleven branchial leaves. Radula with inner surface of innermost lateral tooth smooth or with one or two denticles; only outermost tooth with small branches on its distal part. Large and amorphous accessory gland connecting to atrium.

Description. External morphology ( Figures 2A–B ; 19G–H): body elongated, slightly tapered at posterior portion; up to 17.0 mm long alive, with 1.7 to 2.0 times greater length than width. Mantle densely covered by equidistant and cilindrical caryophyllidia (height: 221 µm to 277 µm); caryophyllidia lower in mantle edge and in center of mantle than those in sides of mantle, with 5–6 spicules that protrude around tubercle, which presents an oval apex ciliate. Rhinophoral and branchial sheaths prominent, covered by caryophyllidia. Rhinophores long with cylindrical apex, 10 to 14 diagonal perfoliations. Gill with eleven retractile, tripinnate branchial leaves, arranged to form a closed branchial circle around high anal cone. Foot narrower than mantle; anteriorly bilabiated and notched on upper “lip”; posteriorly, foot may project beyond mantle in a rounded tail. Oral tentacles conical and elongated. Color of living specimens ranging from whitish gray to white, with several rounded blotches on dorsum, darker than rest of mantle, of irregular sizes and arrangement; ventrally, translucent white; rhinophores and branchial leaves with same tone as mantle with white tips.

Labial cuticle and radula ( Figures 19 A–F): labial cuticle with yellow lateral plates with numerous elongated elements with rounded apex. Radula formula 17 x 14.0. 14 in specimen measuring 14.0 mm in length; lateral teeth hook-shaped; innermost lateral teeth smooth or with one or two denticles on inner surface of teeth; subsequent lateral teeth smooth, larger and more developed in center of rows; four marginal teeth elongated and thin, only outermost tooth presenting small branches on distal part.

Reproductive system ( Figure 20 A–C): hermaphrodite duct connected to convoluted ampulla. Postampullary gonoduct short, connecting to oviduct and prostate. Prostate granular, divided into two parts; a longer, less dense proximal part and a smaller, denser distal part. Deferent duct short and not convoluted, usually thicker than vagina, becoming a tubular ejaculatory portion near base of common atrium with vagina. Accessory gland large, with a not well defined shape, attached to atrium; at base of gonopore accessory gland always with a heart-shaped enlargement and after that two enlarged portions until entering into female gland; sexually immature specimens only having an heart-shape enlargement; accessory gland with slightly concave spine, about 480 µm in length. Vagina elongate and narrow opening in rounded bursa copulatrix. Bursa serially arranged, vaginal duct narrow and not convoluted and connecting to seminal receptacle; uterine duct short. Seminal receptacle slightly shorter than bursa copulatrix.

Biology ( Figure 20 E–F): Egg mass white as a spiral ribbon with 11.0 mm diameter (deposited by a specimen 16.0 mm long), with crenulated border; ribbon with two whorls in counterclockwise direction with numerous rows of many tiny eggs.

Remarks. Jorunna spongiosa sp. nov. fits perfectly in the genus Jorunna , presenting all the diagnostic features of the genus (Camacho-García & Gosliner, 2008), including the dorsum covered by elongated caryophyllidia ( Figs. 19 G–H); a prostate with two portions ( Fig. 20 A); a copulatory spine ( Fig. 20 C); the presence of an accessory gland ( Figs. 20 A–B); and a labial cuticle that can be smooth or armed with jaw elements ( Fig. 19 A).

Jorunna includes 18 valid species, among which Jorunna spazzola , Jorunna ghanensis Edmunds, 2011 and Jorunna glandulosa Edmunds, 2011 are the species known from the South Atlantic to date.

Jorunna glandulosa differs from Jorunna spongiosa sp. nov. in terms of coloration: its mantle is creamy yellow with brown marking and pale brownish spots and the gill is orange with brown spots, whereas the mantle of Jorunna spongiosa sp. nov. is whitish gray to white, with several rounded blotches on the dorsum that are darker than the rest of the mantle, and the gill is the same tone as the mantle, with white tips. Although Jorunna glandulosa (39 × 46.0.46) (up to 7mm in length) is smaller in length than Jorunna spongiosa sp. nov. (17 x 14.0.14) (up to 17mm in length), its radula is longer and broader. In Jorunna glandulosa , the teeth are smooth and hook shaped, whereas Jorunna spongiosa sp. nov. presents innermost lateral teeth that are smooth or display one or two denticles on the inner surface, and the outermost tooth presents small branches on the distal portion.

Jorunna ghanensis differs from Jorunna spongiosa sp. nov. in the color of its mantle, which is yellow-brown with scattered small brown or red-brown spots, suffused with minute white dots, with three or four larger dark brown spots on each side between the rhinophores and gills. Whereas Jorunna spongiosa sp. nov. are whitish gray to white, with several rounded blotches on the dorsum, darker than the rest of the mantle; All of the teeth in Jorunna ghanensis are hamate and lack denticles, in contrast to Jorunna spongiosa sp. nov. that has the innermost lateral teeth smooth or with one or two denticles on the inner surface of the teeth and the outermost tooth presents small branches on their distal part.

Jorunna spongiosa sp. nov. differs from J. spazzola by whitish coloration ( Figs. 2A–B ), although the patterns of blotches are very similar in the two species. In relation to the relative body lengths, Jorunna spongiosa sp. nov. (13.0 mm to 17.0 mm) is longer than Jorunna spazzola (3.0 mm to 9.0 mm). In Jorunna spongiosa sp. nov. the marginal teeth are elongated and filiform and only the outermost tooth presents small branches on its distal part ( Figs. 19 E–F), whereas in J. spazzola all marginal teeth are elongated, thin and branched, and have two or four finger-like projections on their distal part ( Figs. 17 E–F). These differences cannot be interpreted as an ontogenetic variation, because J. spazzola , the smaller species, has branched marginal teeth, whereas Jorunna spongiosa sp. nov., the bigger species, has only one, slightly branched marginal tooth (the outermost one).

In the reproductive system, the main differences are the ampulla shape, the accessory gland, and the shape and size of the spine of the accessory gland: in Jorunna spongiosa sp. nov. the ampulla is elongated and convoluted, the accessory gland is large and has a distal enlarged portion shaped like a heart, and more proximal two enlarged portions until entering into the female gland; the spine is slightly concave, measuring approximately 480 µm in length ( Fig. 20 C). In J. spazzola , the ampulla is rounded and not convoluted, the accessory gland is long and thin, and the spine is straight at the base and curved at the distal portion, and measures approximately 165 µm in length ( Fig. 18 B).

Jorunna spongiosa sp. nov. is similar, in terms of its whitish coloration, to Jorunna tomentosa (Cuvier, 1804) , from France, and Jorunna alisonae Ev. Marcus, 1976a, from Hawaii. Jorunna tomentosa is distinguished by the presence of tiny dark spots on the dorsum, and all of its marginal teeth are smooth, whereas in Jorunna spongiosa sp. nov. the dorsum has rounded blotches ( Fig. 2A ) and the outermost tooth has small branches on its distal part ( Figs. 19 E–F). Jorunna alisonae lacks denticles on the innermost lateral teeth, and has smooth marginal teeth and deformed jaw elements, whereas in Jorunna spongiosa sp. nov. the jaw elements are elongated and rounded in their distal region ( Fig. 19 A).

Figures

FIGURE 17. Jorunna spazzola, SEM photographs; A, detail of the labial cuticle; B – D, detail of the innermost lateral tooth; E – F, marginal teeth; G – H, caryophyllidia. A, C – F (MNRJ 13190); B (MNRJ 13196); G – H (Syntype, MZSP 75960).

FIGURE 18. Jorunna spazzola (Syntype, MZSP 75960); A, general view of reproductive system; B, copulatory spine. Abbreviations: ag, accessory gland; am, ampulla; bc, bursa copulatrix; dd, deferent duct; f, female glands; pr, prostate; s, seminal receptacle; u, uterine duct; va, vagina.

FIGURE 19. Jorunna spongiosa sp. nov., SEM photographs; A, detail of the labial cuticle; B – D, detail of the innermost lateral tooth; E – F, marginal teeth; G – H caryophyllidia. A, C – E, G – H (MNRJ 13781); B, F (MNRJ 13203).

FIGURE 20. Jorunna spongiosa sp. nov.; A, general view of reproductive system; B, detail of the accessory gland; C, copulatory spine; D, juvenile specimen that fed on a sponge, the hole in this sponge represents the location of the feeding; E, specimens copulating in aquarium; F, egg mass. A – B, E – F (MNRJ 13781); C (MNRJ 14971), D (MNRJ 13996). Abbreviations: ag, accessory gland; am, ampulla; bc, bursa copulatrix; dd, deferent duct; f, female glands; go, gonopore; ov, oviduct; pr, prostate; s, seminal receptacle; u, uterine duct; va, vagina.

FIGURE 2. A – B, Jorunna spongiosa sp. nov. (MNRJ 13781, 14 mm); A, dorsal view; B, ventral view; C, Platydoris angustipes (MNRJ 13189, 46 mm), photo: V. Padula; D – F, morphotypes of Taringa telopia; D, (MNRJ 15033, 21 mm); E, (MNRJ 14924, 17 mm); F, (MNRJ 13184), photo: V. Padula; G – H, preserved specimen of Taringa iemanja sp. nov. (MNRJ 13180); E, dorsal view; F, ventral view.