Orchestia stephenseni Cecchini, 1928

Iaciofano, Davide & Brutto, Sabrina Lo, 2016, Re-description of Orchestia stephenseni Cecchini, 1928: designation of neotype and senior synonym to Orchestia constricta A. Costa, 1853 (Crustacea: Amphipoda: Talitridae) by Reversal of Precedence, Zootaxa 4150 (1), pp. 40-60 : 47-51

Orchestia stephenseni Cecchini, 1928

( Figure 7 , 8 )

Orchestia Stephenseni Cecchini, 1928: 7 , pl. 2, fig. 3.— Cecchini 1929: 11.— Ruffo 1951: 1.

Orchestia ghigii Vecchi, 1929: 249 , figs 1–5.— Maccagno 1939: 11.— Mateus & Mateus 1959: 44.

Orchestia Ghigii. — Ruffo 1937: 39.— Ruffo 1949: 323.

Orchestia stephenseni .— G. Karaman 1970: 32.— G. Karaman 1973: 137, figs 1–3.— Koukouras & Russo 1991: 306, table 6.— Bellan-Santini 1993: 752, fig. 515 (key).— Prato, Pastore & Pavia 1995: 63, table 2.— Ruffo 1995: 43.— Stefanidou & Voultsiadou-Koukoura 1995: 603, table 1.— De Matthaeis, Ketmaier, Davolos & Cobolli 1999: 95 (genetics).—Ariani, Camassa & Wittman 2000: 7, 12.— De Matthaeis, Davolos, Cobolli & Ketmaier 2000: 1607 (table 1), 1611, table 4 (genetics).— Zavodnik & Kovačić 2000: 338.— Sezgin, Kocataş & Katağan 2001: 59, tables 2, 3.— Colombini, Chelazzi & Fallaci 2002: 863.— Davolos, Ketmaier, Cobolli & De Matthaeis 2002: 33 (genetics).— Fišer 2002: 38.— Davolos, Iannilli, De Matthaeis & Pietrangeli 2005: 72, fig. 4.— Deidun, Saliba & Schembri 2007: 456 (ecology).— Deidun & Schembri 2008: 19 (ecology).— Akbulut, Ustaoğlu & Çelik 2009: 51, table 1.— Deidun, Saliba & Schembri 2009: 411 (ecology).— Zakhama-Sraieb, Sghaier & Charfi-Cheikhrouha 2009: 5, table 3.— Lucena-Moya, Abraín, Pardo, Hermida & Domínguez 2010: 7.— Sezgin & Aydemir Çil 2010: 9, table 1.— Grintsov 2011: 143 (morphology).—Jelassi, Khemaissia & Nasri- Ammar 2012: 383 (ecology).— Jelassi & Nasri-Ammar 2012: 437 (ecology).

Orchestia constricta Costa, A., 1857: 183 (type locality: Terra d` Otranto , Italy).— Heller 1866: 3.— Stebbing 1906: 542.

Type material. Neotype, male, 21.31 mm, MZPA-AMPH-N_0002, Stagnone of Marsala , Sicily (37°55’03’’N; 12°28’11’’E), among, inside and around banquettes of P. oceanica , July 2013, mediolittoral, hand collected.

Additional material examined. Fifty-three males, MZPA-AMPH-S_0002. Stagnone of Marsala , Sicily (37°55’03’’N; 12°28’11’’E), among, inside and around banquettes of P. oceanica , July 2013, mediolittoral, hand collected.

Type locality. Stagnone of Marsala , Sicily, 37°55’03’’N ; 12°28’11’’E.

Ecology. Mixed sand/gravel, banquette and cobble beaches (slow-drying substrate sensu Pérès & Picard 1964).

Description. Based on neotype, male, 21.31 mm, Morphotype V, MZPA-AMPH-N_0002.

Head as long as peraeonite 1. Eyes present, small, circular. Antenna 1 short, reaching peduncular article 4 of antenna 2; peduncle article 1 as long as wide, article 2 and 3, longer than wide, sub-equal in length; article 1 distoventral and disto-dorsal with one pairs of tooth setae, proximo-ventral with 2 setae in row; article 2 disto-ventral and disto-dorsal with one pair of tooth setae with middle 1 plumose setae, ventral margin with 2 setae; article 3 dorsal with one pairs of tooth setae with middle 1 plumose setae and disto-ventral with one pairs of tooth setae, dorsal margin with one pair of setae and ventral margin with 2 setae in row; flagellum articles 5–6 with final article cone-shaped; all articles with one pairs of tooth setae on disto-dorsal margin; last article with a group of simple setae on apex. Antenna 2 long 1/4 of body size; peduncular articles narrow; peduncular article 5 approximately 1.5 times as long as article 4; peduncle article 3 with bifid setae on all distal margin; peduncle article 4 with sparse bifid setae on all margin; peduncle article 5 ventral margin with 6 groups of bifid setae in row, on dorsal margin 5 groups of bifid setae in row (2 or 3 setae for group); flagellum sub-equal than peduncles, 21-articulated final article is cone-shaped; all article with 4 tooth setae around distal margin; last article with much simple setae on apex. Upper lip (labrum) entire, apical margin with tooth setae. Lower lip (labium) with wide lobes and shoulders apically abundance tooth setae. Mandible stout, incisor 5-dentate (last is bi-dentate), left lacinia 4-dentate, molar finely serrated ( Figure 9 ). Maxilla 1 inner plate narrow with oblique apex and 2 stout apical robust plumose setae; outer plate with 8 tooth setae, medially serrate tooth setae; palp slender 1-articulate. Maxilla 2 inner plate with 1 stout long, plumose seta medially and robust setae distally; outer plate rounded distally armed with tooth setae. Maxilliped inner plates with plumose setae on apical margin with 3 robust setae (tri-dentate); outer plate slightly shorter than basal height in length, with tooth setae apically; palp article 3 rounded apically and densely covered with tooth setae, article 4 absent. On external margin bifid setae are present (see Figure 5 ).

Peraeon. Peraeonite 1–5 subequal in length. Gnathopod 1 coxa anterior margin straight and anterior distally sub-acute, with marginal setae; basis slightly expanded posterodistally with a row of 7 setae on anterior margin and a row of 4 setae on posterior margin; ischium shortest, rounded posteriorly, with 2 groups of setae on posterior margin and with a process on anterior margin; merus with a row of 4 groups of setae on posterior margin; merus and carpus connected by diagonal joint; carpus approximately 1.5 times as long as propodus, slightly curved posteriorly with lobe postero-distally equipped with row of setae and with a row of 3 group of setae on anterior margin; propodus expanded distally with a row of setae and a row of 5 group of setae (4 groups of setae in smallest specimens) on anterior margin, palmar margin (with setae) longer than dactylus; dactylus narrow with a group of setae on inner margin, subchelate. Gnathopod 2 coxa slightly wider than deep, with marginal setae and with postero-proximal process and postero-distal process ('cusp' sensu Bousfield & Hendrycks 2002); basis subrectangular with a row of setae on anterior and posterior margin; ischium narrow with dorsal process; merus little sub-rectangular; carpus distinct; propodus elongate ovoid, slight protuberance near dactylar hinge, palmar margin equipped with row of setae; dactylus curved distally with proximal protuberance and near hinge with a depression; sub-chelate (see Variation par. below for other details). Peraeopod 3–4 coxa sub-quadrate, with marginal setae and with pointed process posterior marginal (cusp); all anterior and posterior margin of peraeopods have group of setae; basis with straight anterior and weakly convex posterior margin; ischium the shortest with posterior marginal notch; merus slightly expanded; carpus approximately 0.7 times as long as merus; propodus slender, slightly longer than carpus; dactylus slender with single setae on inner margin. Peraeopod 5 coxa bi-lobed, anterior lobe wider and slightly longer than posterior one, both with marginal setae; all anterior and posterior margin of peraeopods have group of setae; basis lobed; ischium wider than long with posterior marginal notch; merus as wide as ischium, slightly produced postero-distally; carpus sub-equal to merus in length; propodus narrow, sub-equal to carpus in length; dactylus with single seta enter-marginally. Peraeopod 6 much longer than preceding peraeopods; coxa bilobed, anterior lobe much shorter and narrow than posterior lobe, with marginal setae; all anterior and posterior margin of peraeopod have group of setae; basis rounded, posterior margin moderately expanded; ischium with posterior marginal notch; merus slightly expanded distally; carpus sub-rectangular, sub-equal in length and narrower to merus; propodus very narrow, approximately 1.3 times of merus length, dactylus narrow with seta anterior marginal. Peraeopod 7 longer than peraeopod 6; coxa rounded posteriorly, marginal setae; all anterior and posterior margin of peraeopod have group of setae; basis rounded, posterior margin expanded; ischium with posterior marginal process; merus slightly expanded distally; carpus sub-rectangular, longer and narrower than merus; propodus very narrow, dactylus narrow with seta anterior marginal.

Pleon. Pleopods well developed; peduncles not expanded; bi-ramous, rami shorter than peduncle with more long plumose setae. Epimeron 2 sub-equal in length to epimeron 3. Epimeron 3 posterior margin smooth, posteroventral corner. Uropod 1 peduncle sub-equal than rami, with 4–5 (5–7) robust setae along lateral margin, distolateral peduncular spine-like seta; outer ramus slightly shorter than inner ramus, marginally with 2–3 marginal robust setae; inner ramus with 3–5 marginal robust setae; both rami with rounded apex with group of long stout distal robust setae. Uropod 2 peduncle sub-equal to rami, with setae along lateral margin; inner ramus sub-equal in length to outer ramus; inner ramous with 4–5 marginal robust setae; outer ramus with 1–2 marginal robust setae. Uropod 3 uniramous; peduncle stout, with 4–5 medial and distal robust setae; ramus shorter than peduncle, linear, with 1–4 marginal and 4–7 apical setae. Telson fleshly, with the 2 lobes fused on base; longer than broad, weakly cleft, with lateral and distal bifid setae.

Variation. Morphotype I: Gnathopod 2 propodus trapezoid; palm slightly convex, extending about 40% of posterior margin with a distal small protuberance, where tip of dactylus closes; dactylus smoothly arcuate. Morphotype II: Gnathopod 2 propodus sub-ovate; palm slightly convex, extending about 70% of posterior margin with a distal very small protuberance, where tip of dactylus closes; dactylus slender distally. Morphotype III: Gnathopod 2 propodus ovate; dactylus slender distally, as long as the palm of propodus. Morphotype IV: Gnathopod 2 propodus ovate; dactylus posterior margin with postero-proximal sinus and protuberance. Morphotype V: Gnathopod 2 propodus ovate; palm with postero-proximal sinus; dactylus posterior margin with well-developed postero-proximal sinus and protuberance.

Remarks. The material, originally described by Cecchini (1928), was collected from La Spezia (northern Italy) . However, a holotype was never designated ( Lowry & Fanini 2013); thus, a neotype has been designated from the collection in Sicily (southern Italy) .

Figures

FIGURE 5. Linear regression between body length and number of antenna 2 flagellar articles for each Morphotype.

FIGURE 7. Iconography of Orchestia stephenseni Cecchini, 1928. Male. Morphotype V. Gnathopods 2 of specimens ascribed to Morphotype I – IV are shown. Peraeopod 7 of specimens ascribed to Morphotype I is shown. See text for terminology. Scale bar = 1 mm.

FIGURE 8. Orchestia stephenseni Cecchini, 1928. Male. Details of shapes of palm and dactylus of gnathopod 2, dactylus of peraeopod 3 and peraeopod 4, merus, carpus and propodus of gnathopod 1 and palp of maxilliped.

FIGURE 9. Orchestia stephenseni Cecchini, 1928. Male. Incisor and lacinia mobilis.