Meladema lepidoptera, Bilton, David T. & Ribera, Ignacio, 2017

Bilton, David T. & Ribera, Ignacio, 2017, A revision of Meladema diving beetles (Coleoptera, Dytiscidae), with the description of a new species from the central Mediterranean based on molecules and morphology, ZooKeys 702, pp. 45-112 : 66-73

Meladema lepidoptera sp. n. Figures 3B, 4B, 5B, 6B, 7B, D, 8B, D, 11B, 12B, F, 13B, 14B, 15B, 18A, 20 O–U, 21, 22, 23

Type locality.

France, Corsica, Cap Corse, stream nr. Bettolacce, 42°58'2.4"N 9°24'42.4"E.

Type material

(genotyped specimens only). Holotype ♂: "11 FR Corsica 21.ix.1999// Cap Corse: Bettolacce// 42°58'2.4"N 9°24'42.4"E 250m// I.Ribera & A. Cieslak leg." "DNA voucher// NHM-IRM12E" " Meladema lepidoptera // Bilton & Ribera, 2017//HOLOTYPE" (NMW). Dry card mounted, tissue samples and DNA aliquotes, with same data, in IBE. Sequence data from the holotype has been deposited in GenBank with accession numbers AF428206 (COI-3') and AF428188 (16S ribosomal RNA). Paratypes (13): 1 ♂ "11 FR Corsica 21.ix.1999// Cap Corse: Bettolacce// 42°58'2.4"N 9°24'42.4"E 250m// I.Ribera & A. Cieslak leg. ”“ DNA voucher// NHM-IRM12F" (NMW); 1 ♀ "11 FR Corsica 21.ix.1999// Cap Corse: Bettolacce// 42°58'2.4"N 9°24'42.4"E 250m// I.Ribera & A. Cieslak leg." "DNA voucher// NHM-IRM12C" (BMNH); 1 ♀ "5 FR Corsica 19.ix.1999// Porto-Vecchio, l’Ospedale // 41°39'13.7"N 9°12'41.0"E 690m// I.Ribera & A. Cieslak leg." "DNA voucher// NHM-IRM12A" (CBP); 1 ♀ "5 FR Corsica 19.ix.1999// Porto-Vecchio, l’Ospedale // 41°39'13.7"N 9°12'41.0"E 690m// I.Ribera & A. Cieslak leg." "DNA voucher// NHM-IRM12D" (MNHN); 1 ♀ "5 FR Corsica 19.ix.1999// Porto-Vecchio, l’Ospedale // 41°39'13.7"N 9°12'41.0"E 690m// I.Ribera & A. Cieslak leg." "DNA Voucher// NHM-IRM12g" (IBE); 1 ♀ "9 FR Corsica 19.ix.1999// Ghisoni, road to Campannella// 42°4'8.7"N 9°11'6.0"E 830m// I.Ribera & A. Cieslak leg." "DNA Voucher// NHM-IRM12b" (IBE); 1 ♂ "Toscana (PI) S. Luce// ‘Boso’ de Castagni, s tr. s.// Luce-Castellina Marittima// 3.X.2007 leg. M. Toledo" "DNA voucher// IBE-AN693" (CTP); 1 ♀ "April 2015 Italy Monti della Tolfa// Rio Ippovia della Cicugnola// (pozze ruscellamento)// 42°4'26.27"N 11°56'12.25"E // V. Buono leg." "DNA voucher// IBE-AN760" (CVR); 1 ♂ "I. D’ELBA - POMONTE// Fosso BARIONE// m 250-300// 29.V.94 TOLEDO LGT." [HW] "DNA voucher// IBE-AN692" (CTP); 1 ♂ "3/vi/2014 ITALY Montecristo// 42.334N 10.308E 260m// R. Vila leg." "DNA voucher// IBE-DV289" (IBE); 1 ♂ "3/vi/2014 ITALY Montecristo// 42.334N 10.308E 260m// R. Vila leg." "DNA voucher// IBE-DV290" (ISNB); 1 ♂ "27/v/2009 ITALY Sardinia// Nuoro prov.(Ogliastra historical region)// brook 562m ESE Villagrande Strìsaili (WNW Tortoli)// 39.95084N 9.51912E H. Fery & M. Toledo leg." "DNA voucher// IBE-RA5" (MNCN); 1 ♀ "27.5.2009 Italy, Sardinia// Ogliastra prov., ca. 5 km// WNW Tortoli, (on road// Tortoli - Villagrande Stris.)" "39.93982N 9.59280E// ca 80m, brook// Fery & Toledo leg." "DNA voucher// IBE-RA18" (MNCN). Each with red label " Meladema lepidoptera // Bilton & Ribera, 2017//PARATYPE". All dry card mounted, tissue samples and DNA aliquotes, with same data, in IBE.

Additional material examined

(non-genotyped specimens). France, Corsica: 2 ♂♂, 1 ♀ "11/iv/1993// Corsica Francardo// Mediterranean stream// D. T. Bilton leg." (CBP); 1 ♀ "Calvi// 29.VIII." "Pietra// Maggiore" "KORSIKA// VIII.1955" " Meladema // coriacea Cast.// M/ Balke det. 1990" [Latin name, describer & 90 HW] (NMW); 1 ♂, 2 ♀♀ "12.4.79 Korsika// Pinito, ca 700m// Bach" [HW] reverse "Fery leg." "Mel.// coriacea // Cast." [HW] (NMW); 1 ♀ "12.4.79 Korsika// Pinito, ca 700m// Bach" [HW] reverse "Fery leg." "Mel.// coriacea // Cast." [HW] "coll. Shaverdo" (NMW); 1 ♀ "Korsika// 7.80" [HW] " Meladema // coriacea Cast.// M. Balke 1990" [Latin name, describer & 90 HW] (NMW); 1 ♂ “Corse” [HW] “Reveliere” [yellow, square label, HW] "Coriaceus// Corsica" [HW] "C. Epplsh.// Steind. d." (NMW); 1 ♂ “Corsica” (NMW); 1 ♀ "12.4.79 Korsika// Pinito, ca. 700m// Bach" [HW] "Mel.// coriacea // Cast." [HW] "Coll.// HENDRICH// Berlin" (ZSM). Italy, Sardinia: 5 ♂♂, 3 ♀♀ "Sardinia (CA) Dolianova// Rio Flumini 30.VI.91// leg. Meloni" (CBP, CTP); 3 ♂♂, 1 ♀ "SARDINIEN// Bosa// 24.5-24.6.//1963, Budberg" reverse " Meladema // coriaceum Lap." [HW] (NMW); 1 ♀ "coll. Win-// gelmüller” " coriaceum Lap.// Sardinien" [HW] (NMW); 1 ♂ "Villasimius// Sard. m. 19.9.59// E. Jünger” [19 HW] "A7598// coricae Cast.// det. K. Hoch 1959" [number, Latin name, describer & 9 HW] (ZSM); 1 ♀ "Sardegna// Lode// 28.7.79// S. Gottwalt" [HW] "coll.//HENDRICH// Berlin" (ZSM); 2 ♀♀ "Sardinien: bei Nuvafus,// 09.IX.1978" " Meladema // coriacea // Cast." [HW] "entnommen// 1 Exempl." [HW] "Sardinien// S. Nuvafus// 9.9.78" [HW] (ZSM); 1 ♂, 1 ♀ "Sardinien: S Monte// Limbara. Tempio, 650m,// 28.VIII.1978" " Meladema // coriacea // Cast." [HW] "Entnommen// 1 Exempl." [HW] "Sardinien// Südl. Monte. Liombara// Tempio 650m// 28.8.78" [HW] "Fuss Monte// Limbara 650m// 28.8.78" [HW] (ZSM); 1 ♀ "Sardinien: Lagoatto di// Flumendosa, Villanova// Strisaili, 05.IX.1978" " Meladema // coriacea // Cast." [HW] "Sardinien// Lagoatto di Flumendosa// Villanova Strisaili// 5.9.1978" [HW] (ZSM); 6 ♂♂, 3 ♀♀ " Meladema // coriacea Cast.// Italien/ Sardinien// Giara di Gesturi// - 9.1980// Coll./ leg.// Burmeister" "Sardinien// Giara di Gesturi// 9.1980// leg. Burmeister" [HW] " Meladema // coriacea // Cast." [HW] (ZSM); 1 ♂ " Meladema // coriacea Cast.// Italien/ Sardinien// b. Tempio// Bergbach am// Monte Limbarra// - 9.1980// Coll./ leg.// Burmeister" "Sardinien// b. Tempio// Bergbach am// Monte Limbarra// 9. 1980" [HW] " Meladema // coriacea // Cast." [HW] (ZSM); 2 ♂♂, 2 ♀♀ " Meladema // coriacea Cast.// Italien/ Sardinien// Pass b. Genne// Cruxi// 1.9.1980// Coll./ leg.// Burmeister" "Sardinien// Pass b. Genne Cruxi// 10. [circled]// leg. Burmeister" [HW] (ZSM); 2 ♀♀ " Meladema // coriacea Cast.// Italien/ Sardinien// b. Nuragus// ( Viehtränke)// 3.9.1980// Coll./ leg.// Burmeister" "Sardinien// b. Nuragus// Viehtränke // 3.9.1980 23. [circled]// leg. Burmeister" [HW] " Meladema // coriacea // Cast." [HW] (ZSM); 1 ♂ " Meladema // coriacea Cast.// Italien/ Sardinien// b. Tempio// Bergbach// b. Mnte Limbarra// - 9.1980// Coll./ leg.// Burmeister" "Sardinien// b. Tempio, Bergbach// b. Monte Limbarra// 9/1980 39. [circled]// leg. Burmeister" [HW] ' Meladema // coriacea // Cast." [HW] (ZSM); 1 ♂ "Glasgow University// HUNTERIAN MUSEUM// ex. coll. G.N. Foster" "Sardinia 32T UTH// 04602/44750// S of Mont Minerva// G N Foster 16.10.2006" (CFA); 1 ♀ "27.5.2009 Italy, Sardinia// Ogliastra prov., ca. 5 km// WNW Tortoli, (on road// Tortoli - Villagrande Stris.)" "39.93982N 9.59280E// ca 80m, brook// Fery & Toledo leg." (IBE). 1 ♂ "9 Sardinia, Calangianus 11.iv.2017// stream, way to Pascaredda tomb// 40°54'35.6"N 9°10'12.8"E 435m// I.Ribera & A.Cieslak leg." (IBE); Italy, Elba: 1 ♂ [no head] "Ins. Elba// 1908// Paganetti" (NMW); 2 ♂♂ "Elba: bei Marciana, Bach in// Kastanienwald, 17.IX.1975,// leg.: Schmalfuss" "17.9.75 Elba, bei Murciana// Bach in Kastanienwald// Schmalfuss leg." [HW] " Meladema // coriaceum // Lap." [HW] " Meladema coriacea Cast." [HW] (ZSM). Italy, mainland: 5 ♂♂, 3 ♀♀ " Levante,// Liguria, Italy." "Coll. Odier.// B.M. 1921-288." (BMNH); 1 ♂, 1 ♀ "Levante,// Liguria, Italy." "Coll. Odier.// B.M. 1921-288." " Meladema // coriacea Cast// C.R. Smith det. 1982" [Latin name, describer & 2 HW] (BMNH); 1 ♀ "ITALY: Liguria.//Torr. 2km W. of Pogli,// trib. of Torr. Arroscia, nr. Albenga, 7.iv.1958// J. Balfour-Browne." "Brit. Mus.// 1960-482." [482 HW] " Meladema // coriacea Cast// C.R. Smith det. 1982" [Latin name, describer & 2 HW] (BMNH); 3 ♂♂, 1 ♀ "Italia// Ruta// 2-6. VII.95// A. Fiori" [HW, A. Fiori printed] (NMW); 1 ♀ " coriaceus // Toscana// V. Heyden" [HW] "c. Epplsh.// Steind. d." (NMW); 1 ♂ "S. gimignano// Sienna → Florenz// 3.8.36 Eiselt" [HW] " Meladema // coriaceum " [HW] (NMW); 1 ♂ "San Gimignano// IX 36 EISELT" " Meladema // coriaceum Lap." [HW] (NMW); 1 ♀ "San Gimignano// IX 36 EISELT" (NMW); 1 ♂ "Nervi// 27.III.05" [HW] (ZSM); 2 ♀♀ "Italia// 26.3.05" [date HW] “Nervi” (ZSM); 1 ♀ "Italien// 11.xii.05" [HW] “♀” "Samml. A.// Zimmermann" (ZSM); 1 ♀ [small, circular brown label, no text] “Pisa” [HW] "alte// Sammlung" (ZSM); 1 ♀ "Italia: Umbria, NE Gosparini,// 550m, dry stream, 09.IX.2015// 43°14'31.73"N, 12°6'19.69"E,// leg. Komarek, Beutel (TM7)" " Meladema // coriacea Lap.// det. H. Shaverdo 2016" [Latin name, describer & 16 HW] (NMW). Without locality data: 1 ♀ [small, circular brown label, no text] "Coll. Odier.// B.M. 1921-288." (BMNH); 1 ♀ " coriaceus " [HW] "E Coll.// Curtis" [HW] (BMNH); 1 ♂ "40// 4 2// 2135" [round label, HW] (BMNH). All with " Meladema lepidoptera // Bilton & Ribera// D T Bilton [or I Ribera] det. 2017".

Description.

Size: Holotype TL = 20.74 mm; EL = 15.74 mm; MW = 10.50 mm. Other material examined TL = 19.20-20.99 mm; EL = 14.98-16.38 mm; MW = 9.73-11.39 mm.

Colour. Dorsum dark reddish brown to black (Figure 3B); lateral margins of pronotum, labrum and anterior half of clypeus somewhat paler, sometimes with diffuse lateral maculae. Elytra unicolorous, without distinct mottling even when lifted (Figure 4B). Head with a pair of oval, reddish yellow medial interocular patches, slightly elongated apicolaterally. Antennae and maxillary and labial palpi reddish yellow. Legs dark reddish brown to black with golden yellow setae; large spines somewhat paler. Venter reddish brown to black; gula, meso and metacoxae and trochanters paler.

Head. Labrum shining, with moderate to coarse, sparse punctures. Reticulation absent in apical half, becoming increasingly more evident basally, here forming weakly impressed, transverse meshes. Clypeus and anterior half of frons shining, doubly punctate, without reticulation and with very close, fine and very sparse, coarse punctures. Coarse punctures approximately 5-8x diameter of fine; without visible reticulation. Paired epicranial foveae, one immediately behind the other, on each side of frons, close to lateral margins and immediately behind lateral remnants of frontoclypeal suture. Anterior epicranial foveae transverse, posterior slightly elongate oval; both with cluster of stout, yellow recumbent to decumbent setae. Areas between anterior and posterior foveae with coarse wrinkles. Posterior frons with open, elongate, wrinkled reticulation, especially alongside lateral margins of compound eyes and onto vertex; meshes tumid, with rugose appearance. Internal and posterior borders of compound eyes distinct, raised relative to level of adjacent cuticle. Lateral margins bordered by distinct narrow channel; deeper anteriorly than posteriorly and continuing behind posterior margin of eye onto vertex. Channel with dense punctures, bearing long, stiff, yellow recumbent to decumbent setae.

Pronotum. Posterior margin strongly sinuate laterally (Figure 3B). Surface somewhat shining, strongly rugose. Reticulation meshes large, open, almost isodiametric and relatively flat either side of mid-line on disc; smaller, tumid and more uneven in size and shape towards all margins. Transverse irregular row of medium punctures bearing long, yellow recumbent to decumbent setae 1/5 behind anterior pronotal margin; interrupted briefly in centre, continuing inside lateral margins and inside lateral third of posterior margin. Centre of disc with elongate, narrow, slit-like fovea, sometimes partially interrupted in mid-length. Lateral margins slightly raised, shining, without rugose sculpture and with fine, scattered punctures.

Elytra. Somewhat shining, with dense, transverse, sometimes contiguous, crescentic striolae, giving a very scaly appearance (Figure 3B). Striolae relatively dense throughout, frequently contacting each other laterally on shoulder close to suture (e.g. Figures 5B, 7B, 18A, 21, 22, and relatively dense in mid-elytra close to suture (e.g. Figures 7D, 8D, 18A, 21, 22)). Size of crescentic striolae relatively large, both in shoulder and mid-elytral regions (e.g. Figures 7B, D, 8B, D, 18A, 21, 22). Crescentic striolae becoming denser and somewhat continuous laterally and posteriorly. Surface between crescentic striolae (Figures 5B, 6B) doubly punctate, with very fine, close punctures and medium, very sparse punctures (the latter bearing short, peg-like setae); also with fine, obsolete, open reticulation, usually more evident in apical two thirds, and more evident in some specimens than others. Puncture rows well-marked, continuous almost to elytral apices; punctures shallower posteriorly than anteriorly.

Venter. Prementum shining, tumid in centre, with fine and medium, sparse punctures. Mentum shining; central projection with shallow median emargination. Lateral lobes with medium, sparse punctures, and scattered, whitish recumbent to decumbent setae. Submentum shining, with transverse wrinkles centrally, and elongate wrinkles laterally. Central 1/4 with medium, sparse punctures bearing long, white-yellowish, erect setae. Gula shining, with sparse, shallow, transverse wrinkles; patch of medium-coarse punctures posterolaterally. Genae shining, with obsolete, open, elongate reticulation. Prosternum shining, with irregular transverse ridges laterally. Strongly arched in centre and with fine, moderate to close punctures laterally, bearing long, white- yellowish, recumbent to erect setae; punctures and setae extending in a sparse, irregular row onto process, just below arch. Process lanceolate, tectiform; apex acuminately rounded. Centre of prosternum and process with double punctation of very fine, moderate and medium, very sparse punctures. Pronotal hypomeron shining, impunctate. Elytral epipleurs shining, with fine wrinkles; irregular puncture row close to internal margin, from centre to close to apex; punctures bearing fine, whitish, erect setae. Metaventrite shining, central portion with sparse, transverse scratches and fine to very fine, sparse to very sparse punctures; not clearly forming two size classes. Metaventral process strongly reticulate, with transverse, rugose meshes and traces of fine, sparse punctures; with small central patch of reticulation with very small meshes. Metaventral process relatively broad; apex acuminate and upturned slightly anterolaterally. Metacoxal lines almost reaching anterior border of metacoxae; shallow and interrupted in anterior 1/5. Internal laminae of metacoxae shining, sculpture as on centre of metaventrite. Metacoxal lobes sculptured as internal laminae, strongly rounded, with irregular, elongate field of medium to coarse punctures close to lateral margins, bearing fine, white, recumbent to erect setae. External laminae of metacoxae shining, smooth close to process, but with strong reticulation elsewhere; reticulation meshes very elongate posteromedially, to transverse anteriorly. Abdominal ventrites shining. Ventrites 3-5 with cluster of golden, erect setae anteromedially. Ventrite 1 with elongate reticulation throughout. Ventrite 2 with similar reticulation; absent close to centre. Ventrite 3 with elongate reticulation laterally, becoming transverse close to smooth central 1/5. Reticulation of ventrites 4 and 5 restricted to lateral third and with superimposed elongate furrows. Ventrites 2-5 doubly punctate; very fine, moderate and fine, sparse to very sparse punctures; punctures most evident in areas without reticulation. Ventrites 3-5 with transverse irregular row of long, yellowish, recumbent to decumbent setae laterally. Ventrite 6 (Figure 11B) with very fine, moderate punctures and medium to coarse, sparse to moderate punctures; punctures coarser close to apex. Elongate, semicircular wrinkles and channels apicolaterally. Some punctures in channels bearing elongate, whitish, erect setae.

Male. Foretarsi (Figure 12B) with articulo-setal counts as follows (base to apex): row 1, 7; row 2, 8-10; row 3, 8-10; row 4, 6-8. Number of setae in rows may differ from right to left tarsus in same beetle. Curved, golden setae bordering articulo-setal field dense, particularly basally. Foretarsal claws (Figures 12B, 13B) elongate, curved; interior margin straight or somewhat raised in basal two thirds, strongly curved in apical third. Mesotarsi (Figure 12F) with articulo-setal counts as follows (base to apex): row 1, 7-8; row 2, 8; row 3, 7; row 4, 4 (2 clusters of 2, situated laterally). Curved, golden setae bordering articulo-setal field dense, particularly basally. Mesotarsal claws (Figure 12F) elongate, strongly curved. Abdominal ventrite 6 (Figure 11B) with apex rounded, with very shallow median emargination. Median lobe asymmetrical (Figure 14B), sinuation weak, approximately 1/5-1/4 from apex; ventral margin of apical portion relatively straight in lateral view. Parameres (Figure 14B) with basal portion of inner margin relatively evenly curved; outer and inner margins almost straight over apical two thirds.

Female. As male, except for simple fore and mesotarsi, differently shaped abdominal ventrite 6 (with bluntly pointed apex - Figure 15B). As with M. coriacea , no consistent differences between males and females are evident in terms of elytral sculpture.

Variation. The size and density of the crescentic striolae on the elytra differs somewhat between individuals and localities (Figures 5B, 7B, D, 8B, D, 18A, 21, 22), these being relatively dense in mainland Italy, Corsica and the Tuscan archipelago, and less so in most Sardinian specimens (e.g. Figure 22). The combination of size and density of these striolae is always greater than seen in M. coriacea , however (see above). The degree of curvature of male foretarsal claws differs between individuals, as in M. coriacea , as does the size and shape of the median lobe (e.g. Figure 20 O–U).

Differential diagnosis.

Morphologically almost identical to M. coriacea (see above). Only distinguishable on the size, shape and density of crescentic striolae on the elytra, which give M. lepidoptera sp. n. a very scaly appearance, evident even at relatively low magnification (e.g. Figure 3A vs. 3B). See above for genetic differences between this species and M. coriacea .

Etymology.

From the ancient Greek “lepidos” (λεπίδος, scale, but also referring to roof tiles) and “pteron” (πτερόν, wing). The specific epithet is a noun in the nominative plural.

Distribution.

On the basis of current data, found on Corsica and Sardinia, islands of the Tuscan Archipelago (Elba, Montecristo) and parts of peninsular Italy, from Liguria to Umbria (Figure 23). M. lepidoptera sp. n. is apparently the only species of the genus found on Corsica, Sardinia, Elba and Montecristo (past records of M. coriacea from these islands - e.g. Poggi 1976, Franciscolo 1979, Dettner 2007 - almost certainly referring to this species), but co-occurs with M. coriacea in the Italian peninsula. The exact limits of the distribution of the two species in peninsular Italy remain unclear (see above), but there is morphological evidence suggesting hybridization where they meet, at least in the south (see below). The contact zone between the two species in the north appears to be situated on the Mediterranean coast, somewhere close to the French-Italian border, but to date no intermediate specimens have been seen from this area. Clearly future work, using both genetic and morphological approaches, would be illuminating in understanding the location and dynamics of these contact zones. As with other extant Meladema lineages, this species appears to have originated in the early Pleistocene, colonisation of the Tyrrhenean islands occurring long after the Messinian Salinity Crisis ( Ribera et al. 2003, Sýkora et al. 2017). Sýkora et al. (2017) suggest that M. lepidoptera sp. n. may have originated following the colonization of the Tyrrhenian islands, a hypothesis which should be tested in the future through genetic study of more individuals from peninsular Italy. Sýkora et al. (2017) additionally suggest that this species is characteristic of sites with lower seasonality than is typical for M. coriacea , based on MaxEnt modelling. They note that many of the peninsular Italian localities (obtained from the literature) included in their analyses (from which specimens were not studied) fitted into the climatic space occupied by M. lepidoptera sp. n. (as ' coriacea CSM’), not surprising given our finding that this species does indeed occur on the Italian mainland. Clearly it would be interesting to repeat Sýkora et al.'s (2017) analyses in the future, once the range limits of these taxa are better established. On the basis of current evidence, this species occurs in similar habitats to those occupied by M. coriacea , although the two taxa have not been detected to date in the same locality.