Runcina tingensis, Araujo, Ana Karla, Pola, Marta, Malaquias, Manuel Antonio E, Ballesteros, Manuel, Vitale, Fabio & Cervera, Juan Lucas, 2022

Araujo, Ana Karla, Pola, Marta, Malaquias, Manuel Antonio E, Ballesteros, Manuel, Vitale, Fabio & Cervera, Juan Lucas, 2022, Molecular phylogeny of European Runcinida (Gastropoda, Heterobranchia): the discover of an unexpected pool of complex species, with special reference to the case of Runcina coronata, Zoological Journal of the Linnean Society 194 (3), pp. 761-788 : 780-781

RUNCINA TINGENSIS ARAUJO, POLA, MALAQUIAS & CERVERA, SP. NOV.

( FIGS 4J–M , 5D , 6D , 7C, D )

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 84C29263-8B36-4FA7-A84A-94F4191CE491

Examined material: Holotype: MNCN 15.05 /200114, Tangier (35º47’32”N; 5º49’04”W), Morocco, coll. Naoufal Tamsouri, 22 March 2018, 2 mm living animal, depth 0.5–1.0 m (dissected and sequenced) . Paratype: MNCN 15.05 /91514, Tangier (35º47’32”N; 5º49’04”W), Morocco, coll. Naoufal Tamsouri, 22 March 2018, 1.5 mm fixed animal, depth 0.5–1.0 m (dissected and sequenced) .

Etymology: The name tingensis refers to Tingi, the Greek name of Tangier ( Morocco), the type locality of the species.

External morphology ( Fig. 7C, D ): Living and preserved specimens 2.0 mm and 1.5 mm in length, respectively. Body elongated. Lateral grooves on both sides between notum and foot present. Anterior part of notum (‘head’) straight, rounded on posterior end. Foot as wide as notum, with propodium and metapodium rounded; metapodium extends beyond notum. Ground colour of body light brown. Broad continuous light orange line on edge of notum. Digestive system visible as a broad brownish blotch. White spots concentrated behind eyes and on anterior end of notum forming a triangle. Yellowish dots dispersed on middle of notum. Dark small spots can be present behind anterior white spots on head region and rear part of notum. Eyes inconspicuous. Longitudinal mid-dorsal dark band on foot. Two rounded gills laminae on right side of anus. Gills light brown. Anus located on right lateral side beneath edge of notum, approximately in mid-region of body length.

and 8.8% between R. caletensis and R. aurata ( Table 3). Species delimitation analyses recognized R. caletensis as a valid species ( Fig. 2 ).

Internal anatomy ( Figs 4J–M , 5D , 6D ): Radular formulae 14 × 1.1.1 (MNCN 15.05/91514) and 12 × 1.1.1 (MNCN 15.05/200114). Rachidian tooth bilobed with smooth lateral wings on each side. Central part of rachidian tooth contains pair of pads, each possessing seven to ten denticles. Denticles short, pointed. One inner denticle on each pad conspicuously more developed. Central small depression present between pads; small denticle in-between pads absent ( Fig. 4J ). Lateral teeth denticulate, elongate and hooked shaped with 34–37 long, thin, pointed denticles ( Fig 4L ). Triangular jaws present. Four gizzard plates with eight crests ( Fig. 4M ). Shell absent. Reproductive system monaulic. Female gland mass placed on right side and behind digestive gland. Opens to exterior through short and wide common genital duct ( Fig. 5D ). Male pore opens next to mouth, on right side. Male copulatory organ cylindrical. Short and unarmed penial papilla projects into round atrium. Prostate gland cylindrical and strongly curved with posterior part rounded. Seminal vesicle slender with middle part wider ( Fig. 6D ).

Distribution: Tangier, Morocco (present study).

Remarks: Runcina tingensis resembles R. coronata by its dark colour and presence of small, white and yellow spots on the notum. However, R. tingensis has a broad, continuous, light orange line along the edge of the notum, while R. coronata has lighter regions only on the head and on the back of the notum. Compared with R. aurata and R. caletensis , the dark colour of R. tingensis contrasts with the translucent yellowish colour of these two species. The distribution of white spots is also distinctive among these species. In R. tingensis they form a triangular pattern on the notum ( Fig. 7C, D ), while in the other three species they form a semicircle ( Figs 3 , 7B ). According to our observations, the radula of R. tingensis has, compared with R. aurata , R. coronata and R. caletensis , a prominently more developed denticle in each pad of the rachidian teeth ( Fig. 4J ). The female mass of R. tingensis differs from R. coronata and R. aurata by its elliptical shape and a larger common genital duct ( Fig. 5 ), and its prostate is notably curved and the seminal vesicle enlarged in its central region ( Fig. 6 ). A penial papilla was present as observed for R. caletensis .

The minimum uncorrected p- distances for the COI gene is 7% between R. tingensis and R. coronata , 6.4% between R. tingensis and R. aurata , and 9.9% between R. tingensis and R. caletensis ( Table 3).

Figures

Figure 2. Runcina coronata species-complex. Detail of Clade F extracted from the analyses illustrated in Figure 1. Continuous rectangles, ABGD analysis based on the COI dataset. Dotted rectangles, bPTP analysis based on the COI dataset. *, branches with maximum support. 1, refers to sequences from Genbank.

Figure 3. Living animals of Runcina coronata (A, B) and Runcina aurata (C–F). A, MNCN 15.05/88105, 3 mm in length, Swanage (southern England). B, MNCN 15.05/90423, 4 mm in length, Swanage (southern England) (photos Ian F. Smith). C, MNCN/ADN 118948, 1.5mm in length, La Caleta, Cádiz (south-western Spain; Atlantic Ocean). D, MNCN/ADN 118950, 1mm in length, La Caleta, Cádiz (south-western Spain; Atlantic Ocean). E, MNCN 15.05/88106, 2 mm in length, La Caleta, Cádiz (south-western Spain; Atlantic Ocean). F, MNCN 15.05/88107, 2mm in length, La Caleta, Cádiz (south-western Spain; Atlantic Ocean). Photos A and B, courtesy of Ian F. Smith; photos C–F by Ana Karla Araujo.

Figure 4. Scanning electron micrographs of radula and gizzard plates. A–C, Runcina coronata. A, rachidian teeth (MNCN 15.05/88105). B, lateral teeth (MNCN 15.05/88105). C, gizzard plate (MNCN 15.05/90423). D–F, Runcina aurata. D, rachidian teeth (MNCN 15.05/91500). E, lateral teeth (MNCN 15.05/88106). F, gizzard plate (MNCN 15.05/88106). G–I, Runcina caletensis (MNCN 15.05/200113) G, rachidian teeth. H, lateral teeth. I, gizzard plate. J–M, Runcina tingensis. J, rachidian teeth (MNCN 15.05/200114). L, lateral teeth (MNCN 15.05/200114). M, gizzard plate (MNCN 15.05/91514). Scale bars: A, B, E, J, L = 10 μm; C, F, I, M = 50 μm; D, G = 20 μm; H = 5 μm.

Figure 5. Female reproductive system. A. R. coronata, southern England (MNCN 15.05/90423). B. R. aurata, La Caleta, Cádiz, south-western Spain, Atlantic Ocean (MNCN 15.05/88106). C. R. caletensis, La Caleta, Cádiz, south-western Spain, Atlantic Ocean (MNCN 15.05/200113). D.R. tingensis, Tangier, north-western Morocco,Atlantic Ocean (MNCN 15.05/91514). Abbreviations: FM, female mass; CGD, common genital duct; GO, gonopore.

Figure 6. Male reproductive system. A, Runcina coronata, southern England (MNCN 15.05/90423). B, Runcina aurata, La Caleta, Cádiz, south-western Spain, Atlantic Ocean (MNCN 15.05/88106). C, Runcina caletensis, La Caleta, Cádiz, southwestern Spain, Atlantic Ocean (MNCN 15.05/200113). D, Runcina tingensis, Tangier, north-western Morocco, Atlantic Ocean (MNCN 15.05/91514). Shaded area indicates the presence of sperm. Abbreviations: MO, male opening; PP, penial papilla; PG, prostate gland; SV, seminal vesicle.

Figure 7. Living animals of Runcina caletensis (A, B) and Runcina tingensis (C, D). A, MNCN/AND 118949, 1.5 mm in length, La Caleta, Cádiz (south-western Spain; Atlantic Ocean). B, MNCN 15.05/200113, 3 mm in length, La Caleta, Cádiz (south-western Spain; Atlantic Ocean). C, MNCN 15.05/91514, 1.5mm in length, Tangier (north-western Morocco; Atlantic Ocean). D, MNCN 15.05/200114, 2mm in length, Tangier (north-western Morocco; Atlantic Ocean). A, B images by Ana Karla Araujo; C, D images courtesy of Naoufal Tamsouri.