Jorunna liviae Tibirica , Stroemvoll & Cervera, 2023

Tibirica, Yara, Stroemvoll, Jenny & Cervera, Juan Lucas, 2023, Can you find me? A new sponge-like nudibranch from the genus Jorunna Bergh, 1876 (Mollusca, Gastropoda, Discodorididae), Zoosystematics and Evolution 99 (1), pp. 63-75 : 63

publication ID	https://dx.doi.org/10.3897/zse.99.95222
publication LSID	lsid:zoobank.org:pub:7D011FEE-8B7D-48D5-968A-129CB317B9B2
persistent identifier	https://treatment.plazi.org/id/5B6809CC-32EE-456F-8302-4B8A3D4E0513
taxon LSID	lsid:zoobank.org:act:5B6809CC-32EE-456F-8302-4B8A3D4E0513
treatment provided by	Zoosystematics and Evolution by Pensoft
scientific name	Jorunna liviae Tibirica , Stroemvoll & Cervera
status	sp. nov.

Treatment

Jorunna liviae Tibirica, Stroemvoll & Cervera sp. nov.

Jorunna sp.: Strömvoll, J. & Jones, G. (2019): pg.49.

Material examined.

Holotype: MNCN15.05/200187 (dissected and sequenced), 12.04.2022, Doodles , Ponta do Ouro, Mozambique, depth 15 m, length 20 mm.

Paratypes: MNCN15.05/200188 (dissected and sequenced), 12.04.2022, Doodles , Ponta do Ouro , Mozambique, depth 17 m, length 11 mm. MNCN15.05/94693 (sequenced and tomography), 12.04.2022, Doodles , Ponta do Ouro , Mozambique, depth 15 m, length 20 mm., size 5 mm. MNCN15.05/200189 (dissected and sequenced), 14.04.2022, Doodles , Ponta do Ouro , Mozambique, depth 18 m, length 13 mm. MHNM.MOL.2022.0002, (2 specs.), 23.06.2022, Steps Reef, Ponta do Ouro, Mozambique, depth 16 m, length 30 mm (both) .

Type locality.

Ponta do Ouro, Mozambique (26°51'26"S, 32°53'4"E).

Habitat.

Specimens were collected on submerged subtropical compressed sandstone reefs in Ponta do Ouro, Mozambique.

Diagnosis.

Body elongate-ovulated. Dorsum pale gray to pink, covered on highly dense caryphyllidia; rhinophores short, with up to nine lamellae, ending in a knob apex; six to nine bipinnate branchial leaves encircling the anal pore. Radula with five to seven very thin pectinated outermost teeth bearing long bundled fibrous denticles. Labial cuticle smooth. Copulatory spine with bifid apex.

Etymology.

This species is dedicated to Livia Renée Cornelius, daughter of the second author of this paper.

Description.

External morphology (Figs 1 View Figure 1 , 2 View Figure 2 ). Length varied from 11 to 30mm. Body elongate-ovulated, with gritty texture (Fig. 1A View Figure 1 ). Mantle covered on highly dense caryophyllid, evenly distributed on the dorsum (Fig. 2A View Figure 2 ). Caryophyllidia elongated, formed by five to eight spicules, projecting over tip, forming a crown of approximately 140 µm on the dorsum, taller on the margin of gill sheath (≈ 280 µm). Rhinophoral and branchial sheaths low, margin covered by caryophyllidia (Fig. 1D View Figure 1 ). Rhinophores short, retractable, with six to eight diagonal lamellae with a knob protruding apex (Fig. 1E View Figure 1 ). Gill with six to nine retractile, bipinnate branchial leaves, held vertically and forming a closed circle around the anal pore (Fig. 1F View Figure 1 ). Foot narrower than mantle, bilabiate anteriorly, upper lip bifurcate at center (Fig. 1B View Figure 1 ). Side of the foot covered by spicules (≈ 60 µm), spicules absent on foot sole (Figs 1B, C View Figure 1 , 2B, C View Figure 2 ). Feet do not project beyond mantle in natural crawling position. Oral tentacles small and conical. Dorsum color pale pink to gray. Some specimens covered by pinkish-brown minute dots forming spots distributed on the notum. Gill and rhinophores translucent pinkish-white. Oral tentacle white. Upper lip translucent white with brownish dots. Foot pinkish-white.

Internal morphology. (Figs 3 View Figure 3 , 4 View Figure 4 ) The visceral mass is enveloped by a translucent-white tissue covered by brownish dots. Eye spots are visible by transparency.

Digestive system.

Smooth labial cuticle (Fig. 3A View Figure 3 ). Oral tube long, about twice the size of oral bulb, with a pair of retractor muscles (Fig. 4A View Figure 4 ). Buccal bulb ovate, short, radular sac small and ovate, protruding ventrally, with a pair of strong retractor muscles (Fig. 4A View Figure 4 ).

Radular formula difficult to determinate as outermost teeth are very thin and overlapping each other (Fig. 3B View Figure 3 ). Approximate radular formula is: 24 × 5-7.22.0.22.5-7 for the 13 mm specimen MNCN15.05/200189 and 38 × 6-7.26.0.26.6-7 for the 20 mm specimen MNCN15.05/200187. Rachidian tooth absent. Innermost and lateral teeth are single cusped, hamate, lacking denticles (Fig. 3C View Figure 3 ). Lateral teeth gradually increase in size from the inner teeth (≈ 25 µm) toward the external margin (outermost teeth ≈ 100 µm). Five to seven outermost teeth highly differentiated, very thin, pectinate, bearing 5 to 9 long bundled fibrous denticles (Fig. 3D, E View Figure 3 ).

Oesophagus passing through nerve ring, where it folds. Pair of salivary glands, relatively short, uniform, near the base of oesophagus (4A). Oesophagus connects to oval stomach. Intestine about half of oesophagus diameter. Caecum locate ventrally to stomach. Digestive gland cone-shaped, occupying approximately 30% of visceral mass. Anus opening at the center of gill circle.

Central nervous system.

Central nervous system partially covered by blood gland. This is divided into two parts, anterior part about half the size of posterior part. Cerebral ganglia about half the size of pleural ganglia. Cerebral ganglia and pleural ganglia fused. Pedal ganglia ventrally located connected by a simple pedal commissure. Buccal ganglia short, ventrally located. Rhinophoral ganglia bulb-shaped, about 30% the size of cerebral ganglia. Eyes connected to cerebral gland by short rhinophoral nerve (Fig. 4B View Figure 4 ).

Reproductive system.

Hermaphroditic duct leading to an ampulla long and convoluted, located between female gland and accessory gland. Ampulla branching into short oviduct and prostate. Flattened and ovulated prostate narrowing into a thin deferent duct, expanding into ejaculatory portion. Penis unarmed. Accessory gland size and shape varied according to the specimen, from pear-shaped and similar size to the female gland MNCN15.05/200187 to elongated and half of the size MNCN15.05/200189; in all specimens it narrows into a very thin, highly convoluted tube. Copulatory spine in accessory gland of approximately 1.25 mm (Fig. 3F View Figure 3 ). Vagina with similar length and width than deferent duct, leading to an oval bursa copulatrix. Thin duct near the vagina leads to oval seminal receptacle, about 2/3 of the size of the bursa copulatrix, which connects to a large female gland by a short uterine duct (Fig. 4C View Figure 4 ).

Natural history.

This species has only been seen associated with the sponge A. brevispiculifera , on which the species is very cryptic (Fig. 5A, B View Figure 5 ). They are usually found at the base of the sponge branches but they have also been seen on other parts. When removed from the host sponge, the Jorunna liviae sp. nov. stretches the body curling the mantle toward the middle of the foot, similar to what Miller (1996) observed for J. ramicola . Perhaps this behavior aims to protect the sole of the foot which lacks caryophylliid. The white egg mass is also found on the same sponge and forms a close spiral ribbon of approximately five coils (Fig. 5F View Figure 5 ). A likely undescribed species of nudibranch egg-eater Favorinus sp. has been seen feeding on the J. liviae sp. nov. egg mass (Fig. 5C, D View Figure 5 ). Curiously, most of the time the egg ribbons are found on the tip of the sponge. Perhaps this strategy provides some protection against encrusting organisms due the higher water flux in this part of the sponge. Mating has been observed through July between specimens of different sizes and tonalities (Fig. 5E View Figure 5 ). Jorunna liviae sp. nov. seems to prefer sandy reefs with predominantly hydroids, soft coral and sponges. In Southern Mozambique, the flatter sand reefs have a higher density of sponges than the reefs with predominantly hard coral.

Molecular study and phylogeny.

We successfully amplified the gene COI and H3 of four Jorunna liviae sp. nov. specimens. The phylogenetic trees constructed by BI and ML analyses of single gene datasets (Suppl. material 1) were not conflictive but differed in the ability to resolve phylogenetic relationships. The single gene H3 analysis retrieved the lowest resolution and the concatenate dataset the highest. Nevertheless, all Jorunna species were recovered with more than 50% support in all analysis. In general, the BI analysis better solved the relationship between species, while the ML analysis appears to reflect populational structure. Therefore, the results discussed below are based on the concatenated analysis (Fig. 6 View Figure 6 ), except when stated otherwise.

The family Discodorididae formed a large polytomy. The genus Jorunna was divided in two paraphyletic clades, one containing all specimens of J. funebris (PP = 1; BS = 94) and another clade with the remaining Jorunna species (PP = 0.99; BS = 74).

The COI inter-specific variation (uncorrected p -distance) within the genus varied from 9.08% between J. tomentosa lineage B (LB) and J. artsdatabankia to up 16.92% between J. funebris and J. tomentosa lineage A (LA) (Table 1 View Table 1 ). The COI intra-specific variation of Jorunna liviae sp. nov. ranged from 0.16% to 1.08%. The closest species to Jorunna liviae sp. nov. was J. tomentosa lineage B with a minimum p -distance of 13.06%. ASAP retrieved 10 partitions, in both analysis (COI and concatenate) the partitions with higher score (asap-score 1.50-3) Jorunna liviae sp. nov. was retrieved as a distinct taxonomic unit. Curiously, J. funebris were retrieved as a species complex in all possible partitions.