Arenopontia nesaie, COTTARELLI, 1975

Sak, Serdar, Huys, Rony & Karaytuğ, Süphan, 2008, Disentangling the subgeneric division of Arenopontia Kunz, 1937: resurrection of Psammoleptastacus Pennak, 1942, re-examination of Neoleptastacus spinicaudatus Nicholls, 1945, and proposal of two new genera and a new generic classification (Copepoda, Harpacticoida, Arenopontiidae), Zoological Journal of the Linnean Society 152, pp. 409-458 : 414-421

ARENOPONTIA NESAIE COTTARELLI, 1975

Arenopontia (Arenopontia) nesaie Cottarelli, 1975

Arenopontia nesiae Cottarelli, 1975 :

Martínez Arbizu & Moura (1994: 57) (lapsus calami)

Arenopontia nessiae Cottarelli, 1975 :

Martínez Arbizu & Moura (1994: 63) (lapsus calami)

Arenopontia ciplaki Sak, 2004 (nomen nudum)

Original description: Cottarelli (1975): pp. 65–70; figures 1–11, 13–16, 18–19, 21–23.

Type locality: Italy, Sardinia, near Cagliari, Bay of Quartu S. Elena, Poetto beach .

Material examined: (1) one ♀ dissected on eight slides ( NHM reg. no. 2006. 1953) , one ♂ mounted in toto on slide ( NHM reg. no. 2006. 1954) , one ♂ dissected on eight slides ( NHM reg. no. 2006. 1955) , 22 ♀♀ and 22 ♂♂ preserved in alcohol ( NHM reg. no. 2006. 1956– 1965); (2) > 50 ♀♀ and> 50 ♂♂ preserved in alcohol (deposited in BUZM). All material was collected from Dutlimanı Beach (Marmara Sea), 40°22.479 ′ N, 28°03.080 ′ E, Balıkesir Province, Turkey; leg. S. Karaytuğ and S. Sak, 18 September 2001 .

Redescription

Female: Total body length from tip of rostrum to posterior margin of caudal rami: 341–396 M m (mean = 366 M m, n = 25). Maximum width: 38 M m (mean of 20 individuals = 41 M m), measured at posterior margin of cephalothorax. Body: slender and cylindrical, without clear distinction between prosome and urosome ( Fig. 1A, B). Hyaline frills of thoracic somites weakly developed and crenulated; those of genital double-somite and free abdominal somites strongly developed, and consisting of rectangular digitate lappets ( Figs 1A, B, 2A, B). Genital double-somite ( Figs 1A, B, 2A): slightly longer than wide; without chitinous ribs marking original segmentation; with two mid-dorsal, two lateral, and two ventral pores. Anal somite ( Fig. 3A, B): with two dorsal and two lateral pores. Anal operculum: with minute pinnules along free distal margin ( Fig. 3A). Anus: positioned subterminally between caudal rami. Rostrum ( Fig. 1C): small, broadly subtriangular, tapering distally, with two delicate sensillae.

Caudal rami: approximately twice longer than wide (measured in dorsal view), tapering posteriorly; with a proximal pore dorsally ( Fig. 3A), one pore near the ventral proximal margin ( Fig. 2A), and one pore laterally near the insertion site of seta III ( Fig. 3B); outer distal corner produced into posteriorly directed recurved spinous process, accompanied by outer spinular row at base ( Fig. 3A, B); dorsal surface with flagellate spur-like process near inner margin, accompanied by a few tiny spinules near base ( Figs 1D, 3B). Armature consisting of seven setae: seta I, small; setae II and III, long and naked; seta IV, short, sparsely pinnate, located between seta V and spinous process; seta V, long and with fracture plane; seta VI, small, naked, and located at inner distal corner; seta VII, foliaceous and triarticulate at base.

Antennule ( Fig. 3C): long, six-segmented. Segment 1 with a tiny seta near the anterodistal margin. Segment 2 longest, about 3.5 times longer than wide. Segment 4 with long aesthetasc (32- M m long) fused at base with seta. Distal segment: with seven naked setae (two of which are spatulate) and apical acrothek, consisting of short aesthetasc (20- M m long) and two slender setae. Armature formula: 1-[1], 2-[7 + 1 plumose], 3-[4], 4-[(1 + ae)], 5-[1], 6-[7 + acrothek].

Antenna ( Fig. 3D, E): coxa small, without ornamentation. Allobasis: about 2.7 times as long as maximum width; original segmentation marked by partial transverse surface suture; with two spinular rows, as illustrated. Exopod one-segmented, elongate, with a naked apical seta (about 3.3 times longer than exopod). Free endopod with two spinular rows on anterior surface, and with finer spinules at outer distal corner; lateral armature consisting of two short spines; apical armature consisting of two spines and three geniculate setae, the longest of which with spinules around geniculation, and fused basally to tiny accessory seta.

Mandible: with two-segmented palp ( Fig. 2D); basis elongate with one lateral seta; endopod with one inner, one outer, and three apical setae; all armature elements naked. Gnathobase: with coarse teeth distally, and with one naked seta at dorsal corner.

Maxillule ( Fig. 1E): with praecoxal arthrite bearing two setae and five spines around distal margin. Coxal endite: with two long naked setae. Basis with rami entirely incorporated; palp represented by nine naked setae.

Maxilla ( Fig. 2E): syncoxa with two cylindrical endites; proximal endite with three setae; distal endite with two setae. Allobasis: drawn out into long claw; with one accessory setae. Endopod onesegmented, and with three setae. All elements naked.

Maxilliped ( Fig. 2F): syncoxa small and unarmed. Basis: elongate and unarmed. Endopod with small accessory seta, and with slightly curved claw bearing subterminal spinule.

P1 ( Fig. 4A): intercoxal sclerite long and rectangular. Praecoxa: triangular and naked. Coxa: without ornamentation. Basis: with spinular row near bases of endopod and exopod; anterior surface with a proximal pore and a small inner seta. Exopod: three-segmented; exp-1 and exp-2 with spinules around outer margin; exp-1 longest, with long unipinnate outer spine; exp-2 without outer element; exp-3 with short unipinnate outer spine, a long curved unipinnate spine, and one geniculate seta distally, and one inner, apically penicillate seta subdistally. Endopod: two-segmented, prehensile; enp-1 9.3 times longer than wide, and about twice longer than exopod; with a serrate inner seta in proximal third, and a subdistal spinule along outer margin; enp-2 slightly longer than wide, with a short unipinnate spine, a geniculate claw, and a small inner spinule.

P2–P4 ( Fig. 4B–D): intercoxal sclerites naked, wider in P2, but more deeply concave in P3–P4. Praecoxae: small and naked. Coxae: squarish and without ornamentation. Bases: smaller than coxae, with a spinular row near base of endopod (P3–P4); anterior surface with a pore; outer basal seta absent (P2), plumose (P3), or naked (P4). Exopods: threesegmented; segments with spinular ornamentation, as illustrated; inner distal seta of exp-3 sparsely bipinnate, all other elements unipinnate; P3–P4 exp-3 with anterior pore. Endopods: two-segmented; P2–P4 enp-1 about 1.5, 2.2, and 3.0 times longer than their respective distal segments, with few spinules, as illustrated. P2: enp-1 with a long, apically serrate, backwardly directed seta near proximal inner corner. P2–P3: enp-2 with a long, bipinnate, apical seta. P4: enp-2 with apically serrate seta, fused at base, and long unipinnate seta at outer distal corner. Armature formula as follows: P2, exopod, 0.0.021, endopod, 0.110; P3, exopod, 0.0.021, endopod, 0.010; P4, exopod, 0.0.021, endopod, 0.020.

Fifth legs ( Fig. 2A) closely set together, but not touching in ventral midline. Baseoendopod and exopod: fused, forming a rectangular plate; distal margin with three pinnate setae, middle one markedly shorter than the others, but not vestigial; outer basal seta, long and plumose.

Genital field: positioned near anterior margin of genital double-somite ( Fig. 2A). Genital apertures ( Fig. 2C): fused forming median common slit; closed off by fused P6 forming operculum with three minute spinous processes on either side; copulatory pore located midventrally, close to genital slit; seminal receptacles difficult to discern.

Male: Total body length from tip of rostrum to posterior margin of caudal rami: 320–374 M m (mean = 346 M m; N = 25). Maximum width: 40 M m (mean = 38, N = 20), measured at cephalothorax. Body ornamentation ( Fig. 5A): essentially as in female. Sexual dimorphism: in antennule, genital segmentation, and P5 and P6. Spermatophore length: approximately 35 M m.

Antennule ( Fig. 5B, C): nine-segmented, haplocer; geniculation between segments 7 and 8. Segment 2 longest, and about 2.7 times longer than wide; segment 4 an incomplete sclerite with one modified (fused at base) and one tiny element; segment 5 with three setae plus long aesthetasc (42- M m long) fused basally to a small slender seta; segment 6 with a spinulose spine and long distal seta; segment 7 with three modified spines and a seta; segment 8 with a modified spine; distal segment with seven naked setae (two of which spatulate) and apical acrothek. Setal formula: 1-[1], 2-[7 + 1 plumose], 3-[4 + 2 spines], 4-[1 + 1 modified], 5-[3 + (1 + ae)], 6-[1 + 1 modified], 7-[1 + 3 modified], 8-[1 modified], 9-[7 + acrothek]. Acrothek consisting of short aesthetasc (16- M m long) fused basally to two slender setae.

P5 ( Fig. 2B): with armature as in female, but with middle and inner elements comparatively shorter.

Sixth legs ( Fig. 2B): asymmetrical, with smallest P6 closing off functional gonopore; each with a long plumose seta.

Remarks: Arenopontia nesaie was originally described from Poetto Beach in the Bay of Quartu S. Elena near Cagliari, Sardinia ( Italy). Our material differs from Cottarelli’s (1975) description in some aspects, but these are most likely attributable to deficiencies in the original figures. In the type material the marginal spines on the P5 of both sexes appear shorter; however, the flagellate distal parts of these elements are usually difficult to discern, and it seems conceivable that they were not illustrated correctly in the original description. Similarly, Cottarelli (1975) did not illustrate the spinules at the base of the spur and around the terminal process of the caudal ramus, but such morphological minutiae were generally overlooked prior to the advent of differential interference contrast microscopy. The female antennule has fewer setae on the proximal segments than in the Turkish material, but this can be attributed to the fact that Cottarelli viewed the appendage in dorsal aspect and hence overlooked various setae arising from the ventral surface. The threesegmented mandibular palp, which was considered diagnostic for A. nesaie , was not observed in our material, and requires confirmation. The extra segment boundary indicates a two-segmented endopod, which has thus far not been reported for any other oligoarthran harpacticoid (but see Mitwally & Montagna, 2001; cf. below). It is also noteworthy that Cottarelli (1975) had accidentally rotated exp- 3 in his drawing of the P2. His drawing of the female genital field superimposes external and internal structures; for a more accurate interpretation see Fig. 3C and Martínez Arbizu & Moura (1994: fig. 2c, as A. nessiae ). The Sardinian specimens are somewhat smaller [334 M m (♀), 285–300 M m (♂)] than the Marmara population [341–396 M m (♀), 320–374 M m (♂)], but it is questionable whether this size discrepancy has any significance beyond the range of intraspecific variability.

Arenopontia nesaie appears to be widely distributed in the Mediterranean, with confirmed intertidal records from El Saler (Valencia, Spain) by Martínez Arbizu & Moura (1994, as A. nesiae ), Sardinia ( Cottarelli, 1975), the mouth of the Trigno River on the Adriatic coast (Molise, Italy) by Bruno, Cottarelli & Berrera (1998), and Dutlimanı beach (Sea of Marmara, Turkey) by Sak (2004, as A. ciplaki ; present account). Mitwally & Montagna (2001) provided a redescription of A. nesaie based on specimens collected from three beaches (Bir Masoud, El Mamoura, and El Shatby) near Alexandria, Egypt, but the many deficiencies in their illustrations make it difficult to validate their identification. According to Wells (2007), Mitwally & Montagna (2001) make statements about the setation of P1–P4 that, if true, mean that their material cannot belong to Arenopontia . It is obvious that their atypical setal formula results from a failure to distinguish between ornamentation elements (such as long spinules) and genuine setae/spines. Their reports of an outer seta on P1 enp-1 and P3–P4 enp-1, as well as their claim of four elements on P2 exp-3, are false and do not reflect deficiencies in Cottarelli’s (1975) original description, as claimed by the authors. The elements on the female P5 are distinctly longer than in A. nesaie (but are similar to our specimens), and the caudal ramus appears shorter. The variability illustrated for the male P5 suggests that Mitwally & Montagna (2001) had an amalgam of Arenopontia species in their samples. No information was given on the number of setae on the male P6. The distal segment of the P4 exopod appears rotated in their Fig. 11G. Finally, the mandibular palp is erroneously illustrated as three-segmented (see above). Pending re-examination of more material of the Egyptian populations, A. nesaie Cottarelli (1975) sensu Mitwally & Montagna (2001) is considered species inquirenda in Arenopontia .