Dipturus lamillai, Concha & Caira & Ebert & Pompert, 2019

Concha, Francisco J., Caira, Janine N., Ebert, David A. & Pompert, Joost H. W., 2019, Redescription and taxonomic status of Dipturus chilensis (Guichenot, 1848), and description of Dipturus lamillai sp. nov. (Rajiformes: Rajidae), a new species of long-snout skate from the Falkland Islands, Zootaxa 4590 (5), pp. 501-524 : 513-518

publication ID	https://doi.org/ 10.11646/zootaxa.4590.5.1
publication LSID	lsid:zoobank.org:pub:F484C560-CAE9-4A9E-B408-AEC2C8893DAD
persistent identifier	https://treatment.plazi.org/id/1F6B87A9-FF8C-FFA5-A782-20FBFAEAF8FD
treatment provided by	Plazi
scientific name	Dipturus lamillai
status	sp. nov.

Treatment

Dipturus lamillai sp. nov.

Warrah skate; raya guará

( Figures 7–11 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 View FIGURE 11 , 12 View FIGURE 12 C–D; Table 2 View TABLE 2 )

Holotype. Mature male MNHNCL ICT 7531 ( Fig. 7A, C View FIGURE 7 ), tissue voucher No. FA-46, 78.7 cm TL, collected with bottom trawl in waters off the Falkland Islands, southwestern Atlantic Ocean (Station 2019; 49.61°S, 61.19°W; 162 m), on February 14 th 2016, FV Castelo, cruise ZDLT 1-02-2016 Finfish and Rock Cod Biomass Survey, Joost H. W. Pompert. GoogleMaps

Paratypes. Two specimens: a mature male ( CAS 242403 About CAS ; FA-39), 91.5 cm TL, collected with bottom trawl in waters of the Falkland Islands, southwestern Atlantic Ocean (Station 1271; 53°7.6’S, 60°7.9’W; 515 m), on November 17 th 2013, FV Castelo, cruise ZDLT 1-11-2013 Skate Biomass and Biological Survey, by Francisco Concha: a mature female ( MNHNCL ICT 7532 ; FA-47) ( Fig. 7B, D View FIGURE 7 ), 94.2 cm TL, collected with bottom trawl in waters of the Falkland Islands, southwestern Atlantic Ocean (Station 2031; 49.10°S, 60.72°W; 198 m), on February 15 th 2016, FV Castelo, cruise ZDLT 1-02-2016 Finfish and Rock Cod Biomass Survey, by Joost H. W. Pompert GoogleMaps .

Specimens sequenced. Sequence data for NADH2 were generated for the holotype, both paratypes, and five additional specimens of D. lamillai sp. nov. Information on sex, type status, collection number (GCD), and accession numbers for museum and GenBank of each of the specimens is provided in Table 1 View TABLE 1 .

Diagnosis. A medium-sized species of Dipturus , to at least 107.0 cm TL (FA-7). It is distinguishable from its congeners by the following combination of characters: Dorsal surface of body medium brownish with lighter spots and reticulations ranging from simple (holotype) to complex pattern (female paratype); ocellus in center of each pectoral fin reticulated, margins not well defined. Body, dusky grey ventrally, with light patches around mouth, gills, pelvic girdle, and cloaca; area flanking rostral cartilage membranous and barely translucent; disc relatively broad with angular apices, width 75.2 (73.2; 78.9) % TL; snout elongated. Tail longer in males than in female paratype, 38.4 (37.9) % TL and 35.1% TL, respectively. Ventral head length 36.3 (35.0; 32.7) % TL; pre-orbital snout length 3.2 (3.1; 3.5) times distance between orbits; orbit diameter 0.4 (0.6; 0.4) times inter-orbital width. Dorsal surface of disc in males with scattered and thick dermal denticles over rostral cartilage; small fine dermal denticles on pre- and post-orbit; thin band of dermal denticles on anterior margins of dorsal fins and anterior margins of disc, and from tip of snout to anterior margin of alar thorn patches; thin band of dermal denticles on anterior margins of dorsal fins. In females, dorsal surface of head and anterior margins of disc with small dermal denticles; narrow patch of dermal denticles on medial-dorsal area between girdles, narrow band on anterior margins of dorsal fins. Both sexes with orbital thorns, single nuchal thorn; scapular thorns lacking; one median row of small caudal thorns; single row of lateral thorns on each side of tail, mostly at anterior part of tail in males and all along tail in female paratype; additional row of small and posteriorly directed thorns above lateral tail fold; malar and alar thorns only in adult males. Ventral sensory pores small, distinct, black-edged, not surrounded by greyish blotches, more abundant anteriorly to gill openings, scarce on abdominal area.

Description. Morphometric and meristic data provided for holotype (mature male FA-46) and two paratypes (mature male FA-39 and mature female FA-47) are expressed as FA-46 (FA-39; FA-47). Information corresponds to fixed and fresh specimens of both sexes unless otherwise indicated. Dorsal surface medium brownish with lighter spots and reticulations, ranging from relatively simple (holotype) to complex in pattern (female paratype); ocellus in center of each pectoral fin reticulated, margins not well defined, with light spots encircled by pattern of lighter broken lines with rosette-like appearance, lighter to undistinguishable when fixed. Reticulated patterns more pronounced in fresh specimens ( Fig. 7 View FIGURE 7 A–B). Ventral surface dusky grey, with whitish patches around mouth, gills, pelvic girdle and cloaca; ventral surface of claspers whitish ( Fig. 7 View FIGURE 7 C–D).

Disc rhomboidal, 1.3 (1.4; 1.3) times as broad as long; snout angle in front of spiracles 66.3 (68.7; 71.7) degrees; axis of greatest width 65.3 (65.9; 69.0) % of TL; anterior margin of disc concave anteriorly, moderately convex anterior-laterally to line of orbits, strongly or moderately concave margin just behind line of orbits in males and females, respectively; apex narrowly rounded to sub-angular; posterior margin more convex in males than in females; free rear tip broadly rounded.

Head long, snout narrowly pointed, pre-orbital snout length 7.2 (5.5; 8.7) times orbit length, 3.2 (3.1; 3.5) times distance between orbits; pre-upper jaw length 2.0 (1.8; 2.3) times distance between nostrils. Orbit small, diameter 0.4 (0.6; 0. 4) times distance between orbit width. Spiracles 1.1 (1.7; 1.0) times in orbit diameter; spiracle opening oval ( Fig. 8 View FIGURE 8 A–B). Nostrils semi-circular ( Fig. 8 View FIGURE 8 C–D), inner margins forming low semi-circular tube; anterior nasal flap expanded slightly; anterior margin of flap weakly lobe-like. Posterior lobes forming well developed nasal curtain, produced slightly postero-laterally, slightly concave external margins to lobe-like distally, fringed posterior margins, longer in males than in female paratype, reaching lower lip and upper jaw, respectively ( Fig. 8 View FIGURE 8 C–D). Distance between nostrils 1.6 (1.7–1.7) distance between first gill slits, 1.0 (1.0–1.1) distance between fifth gill slits.

Upper jaw more arched in males than in female paratype; in both sexes, lower jaw convex and indented at symphysis ( Fig. 8 View FIGURE 8 C–D). Teeth uni-cuspid, with sub-circular bases, arranged in longitudinal rows in both sexes; cusps of medial teeth long, sub-conical, bluntly pointed, posteriorly and lingually directed in both upper and lower jaws; cusps of lateral teeth oblique and almost flat; cusps of males longer and narrower than in females.

Pelvic fins of medium size, deeply forked ( Fig. 9 View FIGURE 9 A–B); anterior lobe relatively short, slender, bluntly pointed distally 0.7 (0.7–0.8) times posterior lobe, lateral margin entire, inner margin deeply incised; posterior lobe moderately elongate, longer in mature males than in females, 20.7 (20.4–17.8) % of TL, lateral margin weakly convex to straight in males and weakly incised. Claspers elongate, 31.6 (29.4) % TL, moderately robust at shield, slightly depressed at tips; glans noticeably expanded; apopyle and hypopyle visible in external lateral view. Internal components: cleft, shield, slit, spike, spur, and rhipidion; dermal denticles absent ( Fig. 9D View FIGURE 9 ).

Tail relatively short, length from rear of cloaca to tip 0.6 (0.6; 0.5) times distance from tip of snout to rear of cloaca. Tail narrows posteriorly ( Fig. 9 View FIGURE 9 A–B), width at pelvic fin axils 1.6 (1.4; 1.4) times width at mid-length, 1.6 (1.7; 1.6) times width at first dorsal fin origin, width 1.7 (1.7; 1.7) times height at insertion of pelvic fin, 2.8 (2.3; 2.8) times height at mid-length, 2.8 (2.6; 2.6) times height at first dorsal fin origin. Tail in males oval at base, more flattened dorsally, more depressed and ventrally flattened at mid-length and triangular with flattened base at interdorsal space; in females oval and more equally convex dorsally and ventrally at the base, less expanded at midlength and triangular at inter-dorsal space. Lateral tail fold narrow, relatively long-based, similar in males and females; originating as a low membranous ridge beside or slightly behind pelvic fin, terminating at tail tip, not obviously broader at any point along its length, maximum width about half height of caudal fin in holotype and about as wide as caudal fin height in female paratype.

Dorsal fins of moderate size, similar shape and size, and not racked ( Fig. 10 View FIGURE 10 A–B); first dorsal fin slightly taller and more upright than second in holotype; fins subequal in size and similar in shape in paratypes; first dorsal-fin height 1.2 (1.1; 1.1) times in base length; anterior margins of both fins long and weakly convex, apices broadly rounded; posterior margins shorter than anterior margins; free rear tip broadly rounded; second dorsal-fin base slightly shorter in male type specimens and subequal or only marginally longer than first dorsal-fin base in female paratype; inter-dorsal space moderate in type specimens; rear tip of first dorsal fin not overlapping base of second; distance from first dorsal-fin origin to tail tip 2.8 (2.4; 3.0) times first dorsal fin base length, 6.2 (5.2; 5.6) times caudal fin length; first dorsal fin base 2.2 (2.2; 1.9) times caudal-fin length; posterior end of second dorsal fin overlapping with caudal fin origin in both sexes. Epichordal caudal fin lobe present, long-based, low, relatively uniform in height along its length, dorsal margin weakly convex, posterior margin vertical in males, pointed in female paratype, connected sub-basally to second dorsal fin by a low membranous ridge; hypochordal caudal lobe absent. Lateral tail fold subterminal in males and terminal in female paratype ( Fig. 10 View FIGURE 10 A–B).

Adult males with 5 small orbital thorns with oval base and sharp tips; 2 pre-, 2 mid- and 1 post-orbital; pre- and post-orbital thorns flanked by dermal denticles; female paratype with rosette of 6 orbital thorns; 2 pre-orbital, 3 mid-orbital, and 1 post-orbital ( Fig. 8 View FIGURE 8 A–B). Malar and alar thorns only in males; malar thorns 6 (10), very sharp, not embedded, not aligned; alar thorns 10 (18), medially-posteriorly directed, set in about 3 longitudinal rows, some embedded, longer than malar thorns, tips very sharp ( Fig. 10 View FIGURE 10 C–D). Female paratype with single row of 4 median-dorsal thorns and single row of 6 to 8 lateral-dorsal thorns; about 4 posterior-pectoral thorns anterior to rear margin of pectoral fins; few scattered oval-based thorns over pelvic fins ( Fig. 11 View FIGURE 11 ). Caudal thorns of both male type specimens well developed; single row of 20 (25) posteriorly directed caudal thorns extending in linear series of pairs from behind of pelvic girdle area to first dorsal fin; parallel rows of about 6 largely spaced lateral-caudal thorns on each side of central row behind pelvic axil; female paratype with 2 rows of 7 lateral-dorsal thorns behind pectoral girdle; medial-dorsal thorns continuing with caudal thorns; single medial row of 22 caudal thorns, single row of about 14 lateral-caudal thorns on each side, closely spaced on anterior half of tail, more widely spaced posterior half of tail; additional row of more widely spaced and sharp thorns over lateral tail fold from the line of posterior margin of pelvic fins to second dorsal fin; 3 (2; 2) inter-dorsal thorns.

Dermal denticles of males poorly developed and scarce. In male holotype, small denticles on tip of the snout and over rostral cartilages, 2 small patches in front of orbits, and 1 in front and 1 behind spiracles; dense, narrow band along antero-lateral margin of disc, merging anteriorly to malar thorns, reaching to about half of anterior margin of pectoral fin; maximum width about one-fourth orbit diameter; no denticles on remainder of disc or tail; narrow band of fine denticles on anterior margin of dorsal fins and broadly spaced caudal fin. Ventrally, denticles over most of head, more densely distributed over rostral cartilage and along disc margin to level of about first gill slits. Dermal denticles of female paratype covering most of dorsal surface from snout tip to nuchal thorn, medialdorsal area and on anterior and upper margins of dorsal and caudal fins; ventrally, dermal denticles cover most of ventral surface of the head including gill openings, sparse over abdomen, slightly dense patch surrounding cloaca; tail lacking dermal denticles.

Meristics. Based on adult male holotype and female paratype in parentheses as follows: tooth rows in upper jaw 38 (35); tooth rows in lower jaw 36 (35). Pectoral-fin propterygial radials 33 (33); mesopterygial radials 15 (14); metapterygial radials 37 (32); total pectoral radials 83 (79). Pelvic-fin radials 20 (20). Trunk vertebrae 25 (27); pre-dorsal caudal vertebrae 61 (62); vertebrae between origins of dorsal fins 29 (18); total vertebrae about 130 (134).

Size. Largest known specimen a female 114.0 cm TL (FA-7, measured fresh), captured at 171 m depth and discarded after measurements were taken.

Distribution. Species known from the slopes of the southwestern Atlantic Ocean adjacent to the Falkland Islands.

Etymology. This species is named in memory of Julio Lamilla, a Chilean biologist who devoted his life to teaching and research focused on the biology and conservation of chondrichthyans, especially batoids. The proposed common name is Warrah skate, or Raya guará, in reference to the extinct Falkland Islands Wolf, the Warrah ( Dusicyon australis [Kerr 1792]).

Comparisons. Among its congeners, D. lamillai sp. nov. most closely resembles D. chilensis . The two species can be distinguished as follows: whereas the dorsal surface of the disc of D. lamillai sp. nov. is reticulated in appearance due to the presence of numerous light brown spots that can fuse to form lines, the dorsal surface of the disc of D. chilensis is mostly plain brownish with slight mottling. Whereas D. lamillai sp. nov. bears a dark, reticulated ocellus-like blotch on each pectoral fin, the pectoral fins of D. chilensis bear an irregularly shaped purple to red ocellus with solid margins. Furthermore, the distance between the snout tip and cloaca is longer (61.6–64.9 versus 57.8–60.8 % of TL, respectively), while the distance between the cloaca and tail tip is shorter (35.1–38.4 versus 39.2–42.2 % of TL, respectively) in D. lamillai sp. nov. than in D. chilensis . The dermal denticles of both species are similar in size and shape. However, the area covered and the distribution of the denticle patches differ in both sexes between and within species; most conspicuously, the dermal denticles cover a much smaller area of the disc of D. lamillai sp. nov. in both sexes than they do in D. chilensis ( Fig. 12 View FIGURE 12 C–D).

Dipturus lamillai sp. nov. differs from the three other species of Dipturus reported from the waters off the Falkland Islands (i.e., D. argentinensis , D. leptocaudus , and D. trachydermus ) in the distance between orbits (6.4–(6.4–6.6 versus 5.1, 3.9, and 4.9 % of TL, respectively), in the distance between spiracles (7.7–8.1 versus 6.0, 6.2, and 6.5 % of TL, respectively), and also in mouth width (9.3–10.3 versus 8.1, 7.3, and 8.5 % of TL, respectively). Moreover, both the dorsal and ventral surfaces of the body of D. lamillai sp. nov. are partially covered with fine dermal denticles whereas those of D. trachydermus are almost fully covered with dermal denticles of different sizes.

D. lamillai sp. nov. also differs from D. brevicaudatus n. comb. from the coast of Buenos Aires, Argentina. Based on the original description by Marini (1933), the two species differ in coloration. Whereas the dorsal surface of the disc of D. lamillai sp. nov. is medium brownish with multiple lighter spots and reticulations, that of D. brevicaudatus n. comb. was originally described as uniform brownish, although it was subsequently redescribed (under the name Zearaja brevicaudata View in CoL ) as grayish by Gabbanelli et al. (2018). However, morphometric comparisons are difficult to make between D. lamillai sp. nov. and the recently resurrected D. brevicaudatus n. comb. as redescribed by Gabbanelli et al. (2018). This is largely because the measurements presented by these authors are combined for juvenile, subadult, and adult specimens of both sexes, and thus do not allow for comparisons of specimens of the same size or same sex of both species. In addition, although measurements are presented for the holotype specimen, that specimen is a juvenile female (32.4 cm in TL) and those measurements are not comparable to those for the holotype of D. lamillai sp. nov., which is an adult male.

Molecular analysis. Intraspecific p-distances across the 1,043 bp of NADH2 sequence were as follows: D. chilensis View in CoL (n=12) 0–5 bp, with a mean of 2.7 bp; D. lamillai sp. nov. (n=9) 0–4 bp, with a mean of 1.6 bp; D. nasutus View in CoL (n=3) 0–2 bp with a mean of 1.3 bp. Interspecific p-distances were as follows: D. lamillai sp. nov. and D. chilensis View in CoL 28–32 bp with a mean of 29.4 bp; D. lamillai sp. nov. and D. nasutus View in CoL 33–35 bp with a mean of 33.4; D. chilensis View in CoL and D. nasutus View in CoL 8–14 bp with a mean of 11.1 bp.

The Neighbor-Joining tree resulting from analysis of NADH2 data is shown in Figure 13 View FIGURE 13 . Our eight specimens of D. lamillai sp. nov. from the Falkland Islands were found to cluster together away from the cluster composed of our three specimens of D. nasutus from New Zealand and the cluster composed of our 11 specimens of D. chilensis from Chile. GenBank specimen No. KJ913073 View Materials , collected from Chile by Vargas-Caro et al. (2016a), was found to nest among the latter specimens. However, GenBank specimen No. KF748508, collected from raw fillets at a skate restaurant in Seoul, Korea ( Jeong & Lee 2016), was found to nest among our specimens of D. lamillai sp. nov.