Sepiola boletzkyi Bello & Salman, 2015, sp. nov.
Makaleler > Tam Makale · 2015
Yazarlar: Bello, Giambattista, Salman, Alp
Zenodo (CERN European Organization for Nuclear Research), Uluslararası, 2015
Özet
Sepiola boletzkyi sp. nov. urn:lsid:zoobank.org:act: A6A9644D-61E6-4964-9460-A8037035391D Figs 2–7, Tables 1–2 Diagnosis Sepiola with biserial suckers on all arms, including tips of arms IV. Tentacle clubs with six oblique rows of equal-sized suckers. Hectocotylus typical of the Sepiola atlantica group sensu Naef (1923) (Fig. 1): (1) three regular equal-sized suckers in basal part; (2) copulatory apparatus with roundish dorsal tubercle, weakly developed, complemented by broad lobe, dorsomedial to tubercle; (3) sequence of modified suckers in dorsal row of distal part: (a) two small, (b) six markedly enlarged, (c) one small and (d) two enlarged suckers; (4) no dorso-lateral groove on medial side of distal part. Bursa copulatrix moderately large and ear-shaped, anteriorly extended below the left light-organ, with a large fungiform process towards mantle wall posterior to gill insertion. Etymology From the family name of the eminent teuthologist Sigurd von Boletzky, in recognition of his enormous contribution to teuthology. Material examined Holotype ♂, ESFM-CEP/1994-1, mature, ML: 20 mm fresh, 16.8 mm preserved. Paratype ♀, ESFM-CEP /1994-2, immature, ML: 19 mm fresh, 17.2 mm preserved. Same locality as holotype. Type locality TURKEY: Gulf of Ildir, Aegean Sea, eastern Mediterranean Sea, off Sifne (Çeşme District, Izmir Province), 38°19'32"N 26°24'14"E, on a sandy bottom covered by eel-grass, Zostera sp., at a depth of 2 m, Apr. 1994. Description Medium size Sepiola; maximum recorded ML = 20 mm, male (fresh specimen); maximum recorded TL, without tentacles = 40.5 mm, male (arms are variously curled up in both specimens). Tentacles exceed TL by 6–9 mm (tentacle and clubs are variously curled up in both specimens). Measurements are reported in Table 1. Body shape corresponds to general shape of NE Atlantic-Mediterranean Sepiola species (Fig. 2). Mantle sac-shaped, broadly rounded at posterior end, length exceeds width, outline U-shaped. Dorsal mantle margin fused to head by cutaneous nuchal band 27–31% of ML. Ventral mantle margin very slightly sinuate, with very low barely visible rounded projection on each side of funnel (Fig. 2). VML approximately 89-98% of ML. Fins typical for Sepiola, each inserted midway along sides of mantle, broadly rounded; fin length slightly exceeds half ML, fin width about 70–80% of fin length, insertion line about 60% of overall fin length. Head width 65–69% of ML in both specimens. Eyes large, bulging beyond sides of the head, covered by corneal membrane and bordered by secondary eyelid. Funnel long about 60% of ML, covered posteriorly by ventral margin of mantle, funnel free length about 40% of ML; distal end does not reach junction of ventral arms. Arm formula II = III> IV> I in both specimens. Arms slightly longer in male than in female. Suckers stalked, alternately placed in two series on oral side of all arms, including distal-most part of arms IV. Brachial crown of mature males displays sexual dimorphic features (see below for detailed description). Arm web reduced; encloses base of tentacles between arms III and IV. Tentacles thin and delicate. Tentacular club longitudinally lined by protective membranes more developed and ventrally trabeculate (width 1.5–2 mm); distal third of club abruptly tapered, elongate; club suckers equal sized in six oblique rows (Fig. 3). Overall skin colouration pale violet brown; most chromatophores not expanded. (Actual colouration undoubtedly altered by several year storage in ethyl alcohol.) No particular chromatophore distribution pattern observed. Mantle-locking apparatus straight, as typical for the genus, long about ¼ ML. Gladius positioned sagittally on inner face of dorsal mantle, encased in shell sac (see Bizikov 2008 for general description of sepiolid gladius). Gladius reduced, extends from anterior mantle margin to about 45% of ML, posterior tip does not reach posterior end of mantle (as is typical for the genus). Gladius shape similar to those reported for S. bursadhaesa (Bello 2013) and S. aurantiaca (Jatta 1896) (Fig. 4). Chitinous rachis light tan-coloured, widely open V-shaped in cross section. Gladius bluntly pointed at anterior extremity then gradually enlarges to reach width of about 4% of GL (0.32 mm in examined specimen); posteriorly, two sides of rachis run almost parallel to about 55% of GL and subsequently converge to a point short of posterior end. Point where rachis starts to narrow corresponds to anterior insertion of thin and transparent lateral plates. Posterior part of gladius spear-head shaped where rachis is the shaft and lateral plates the two lateral blades that taper posteriorly to a narrow point exceeding the convergence point of the rachis by about 2.5% of GL. Beaks indistinguishable from those of other NE Atlantic-Mediterranean Sepiola species (cf. Açik & Salman 2010) (Fig. 5). Female beak measurements are shown in Table 2. Upper beak rostrum uniformly curved; jaw angle obtuse; wing long as anterior lateral wall margin, shoulder (cutting edge) straight, its margin neatly separated at an obtuse angle from rostrum; no grooves at hood sides; no lateral wall fold; most of lateral wall, posterior part of hood and inferior part of wing transparent. Lower beak comparatively wide; rostrum with blunt tip; jaw edge profile convex, jaw angle indistinct; blunt tooth on shoulder; no notch in hood; lateral wall without fold or ridge, roughly rectangular with lower edge slightly convex, corner faintly produced; wall and wings transparent. Male Mature. Spermatophores 6.5 mm long. Mantle cavity does not show any unique traits that allows it to be distinguished from other Sepiola species. Brachial crown dimorphic. Left arm I hectocotylized (see below), arms II bear 6 pairs of enlarged suckers in middle third; arms III not evidently more robust than remaining arms and not bent inward (contrary to several Sepiola species); arms IV bear 3 pairs of enlarged suckers in middle third. Hectocotylus (left arm I) shorter than right arm I. Basal part (refer to diagram in Fig. 1) bears three equal-sized, not markedly enlarged, suckers, two in ventral and one in dorsal row (the latter missing in holotype as result of damage) (Fig. 6A). Copulatory apparatus formed by fusion of four suckerless stalks, elongated and curved medially, projecting away from arm; ventral-most ones correspond to third and fourth stalks of ventral row; dorsal-most ones derive from second and third stalks of dorsal row, modified into roundish tubercle (Fig. 6 A–B). Copulatory apparatus complemented by broad smoothpointed triangular lobe, dorsomedial to tubercle, formed from more than one dorsal suckerless stalks fused with each other (i.e., likely fourth, fifth and sixth stalks of dorsal sucker row); lobe forms groove with tubercle (Fig. 6 B–C). Distal part of hectocotylus somewhat bent, narrow (i.e., two rows of suckers not spread apart to form a spoon-like widening) (Fig. 6A). Arm tip blunt. No groove on hectocotylus lateral side facing right arm I (Fig. 6B). First two suckers of dorsal row (Fig. 6A, suckers 1–2) in distal part smaller than facing suckers of ventral row; followed by six markedly enlarged (Fig. 6A, suckers 3–8), one small (smaller than facing ventral row suckers) (Fig. 6A, sucker 9), two enlarged suckers (Fig. 6A, suckers 10–11). All enlarged suckers about the same size. Distal to enlarged suckers, remaining eight suckers gradually taper to arm tip. Sucker stalks of enlarged suckers proportionally larger and elongated. Suckers of ventral row regularly sized. Female Immature. Bursa copulatrix large, roughly ear-shaped, longer than wide; anteriorly extends below left light-organ lens, posteriorly reaches posterior end of mantle cavity (most probably this is not so in mature females with enlarged ovary), medially reaches sagittal mantle cavity septum (Fig. 7A). Folds converge towards centre of bursa where they deepen into a longitudinal opening. Posterior half of bursa bordered by elevated rim; contour elliptical, slightly pointed (like a barge prow). Large fungiform process, towards mantle wall rear of gill insertion, sticking out of bursa laterally from converging folds; stalk of process longitudinally folded; distal end larger than stalk, flat, roughly triangular with rounded corners, might be fused with mantle wall (slight possible scar on it) (Fig. 7B). Remarks Sepiola boletzkyi sp. nov. can be distinguished from other species in the genus based on the hectocotylus and the bursa copulatrix. As discovered by Naef (1912a, b, 1923) these copulatory organs are speciesspecific, hence they discriminate the Sepiola species from each other (see also Bello 1995, 2013). In particular S. boletzkyi sp. nov. belongs to the Sepiola atlantica group as defined by Naef (1923), characterized by the peculiar morphology of the male copulatory apparatus (Fig. 1). The male S. boletzkyi sp. nov. differs from all other species in the S. atlantica group because it is unique in exhibiting simultaneously the characters (1) homomorphous tip of ventral arms and (2) enlarged suckers of the dorsal row of the hectocotylus distal part that are subdivided into two groups. Character 1 is shared by S. affinis, S. bursadhaesa, S. intermedia, S. robusta and S. rondeletii as opposed to S. atlantica, S. steenstrupiana and S. tridens; character 2 is displayed only by S. atlantica and S. tridens as opposed to all other species. It is not clear to which Sepiola species S. boletzkyi sp. nov. is closer because this new sepioline differs from all four subgroups delineated by Bello (2013) within the atlantica group. Although it shares with S. atlantica + S. tridens the presence of several enlarged suckers of the dorsal row of the hectocotylus distal part (character 2), it neatly differs from them because of the homomorphous tip of ventral arms (character 1). Moreover the grouping of the enlarged suckers in S. boletzkyi sp. nov. diverges from that of the other two species for the number of suck