Arenopontia anatolica, Sak & Karaytuğ & Huys, 2024

Sak, Serdar, Karaytuğ, Süphan & Huys, Rony, 2024, A revision of the genus Arenopontia Kunz, 1937 (Copepoda, Harpacticoida, Arenopontiidae), including the description of five new species, Zootaxa 5433 (1), pp. 1-50 : 10-17

publication ID	https://doi.org/ 10.11646/zootaxa.5433.1.1
publication LSID	lsid:zoobank.org:pub:06E5A735-A276-41D7-A9EE-B09642D953B6
DOI	https://doi.org/10.5281/zenodo.10953768
persistent identifier	https://treatment.plazi.org/id/7F0E3C20-D032-4342-BAB9-33EDDC81FFC3
taxon LSID	lsid:zoobank.org:act:7F0E3C20-D032-4342-BAB9-33EDDC81FFC3
treatment provided by	Plazi
scientific name	Arenopontia anatolica
status	sp. nov.

Treatment

Arenopontia anatolica sp. nov.

https://zoobank.org/ 7F0E3C20-D032-4342-BAB9-33EDDC81FFC3

( Figs 2–6 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Type locality. Türkiye, Sakarya Province (Black Sea coast), Caferiye (41°04.365’ N, 30°56.329’ E); sandy beach GoogleMaps .

Material examined. Holotype ♀ (dissected on six slides) ( NHMUK reg. no 2024.1000) . Paratypes are 1 ♂ dissected on six slides ( NHMUK reg. no 2024.1001), 1 ♂ dissected on four slides ( BUZM), 5 ♀♀ and 2 ♂♂ in ethanol ( NHMUK reg. nos 2024.1002–1008), and 30 ♀♀ and 8 ♂♂ in ethanol ( BUZM); all collected at type locality; leg. S. Sak and S. Karaytuğ, 06 July 2001 .

Description of female. Total body length from tip of rostrum to posterior margin of caudal rami 257–349 μm (mean = 303 μm; n = 35; holotype = 347 μm). Maximum width 43 μm measured near posterior margin of cephalothorax. Body slender and cylindrical, without clear distinction between prosome and urosome ( Fig. 2A, B View FIGURE 2 ). Hyaline frills of thoracic somites weakly developed and crenulated, those of genital double-somite and free abdominal somites strongly developed and consisting of narrow rectangular non-digitate lappets ( Figs 2A, B View FIGURE 2 ; 6C View FIGURE 6 ). Genital double-somite ( Figs 2A, B View FIGURE 2 ; 6C View FIGURE 6 ) 1.2 times longer than wide (measured in dorsal aspect); without chitinous ribs marking original segmentation; with two middorsal, two lateral and two ventral pores. Anal somite ( Figs 2A, B View FIGURE 2 ; 5A View FIGURE 5 ) with two dorsal and two lateral pores. Anal operculum pinnate; with minute spinules along free distal margin ( Fig. 5A View FIGURE 5 ). Anus positioned subterminally between caudal rami. Rostrum ( Fig. 2B View FIGURE 2 ) small, broadly subtriangular, tapering distally, with two delicate sensilla.

Caudal rami 2.5 times longer than wide (measured in dorsal view from anterior margin to apex of spinous process), tapering posteriorly; with a pore dorsally ( Fig. 5A View FIGURE 5 ), near ventral proximal margin ( Fig. 6C View FIGURE 6 ) and laterally near insertion site of seta III ( Fig. 5B, E View FIGURE 5 ); outer distal corner produced into posteriorly directed, recurved spinous process, accompanied at base by outer spinular row ( Fig. 5B, E View FIGURE 5 ); dorsal surface without spur-like process but with few spinules posterior to insertion of seta VII ( Fig. 5A View FIGURE 5 ). 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 posterior spinous process; seta V long, with proximal fracture plane and few long setules in middle third ( Fig. 5E View FIGURE 5 ); seta VI small, naked and located at inner distal corner; seta VII distinctly foliaceous and tri-articulate at base.

Antennule ( Fig. 3A View FIGURE 3 ) long, six-segmented. Segment 1 with a small seta near anterodistal margin. Segment 2 longest, about three times longer than wide. Segment 4 with long aesthetasc (L: 26 μm) fused at base with seta. Distal segment with seven setae (none distinctly spatulate) and apical acrothek consisting of short aesthetasc (L: 17 μm) and two setae. All setal elements naked except for plumose seta on dorsal surface of segment 2. Armature formula: 1-[1], 2-[7 + 1 plumose], 3-[4], 4-[(1 + ae)], 5-[1], 6-[7 + acrothek].

Antenna ( Fig. 3B, C View FIGURE 3 ). Coxa small, without ornamentation. Allobasis about 2.8 times as long as maximum width; original basis-endopod boundary marked by partial transverse surface suture at base of exopod; basal part with two groups of small spinules along abexopodal margin. Exopod one-segmented, elongate, with a naked apical seta (about 2.25 times longer than exopod). Free endopodal segment with two spinular rows on medial surface and larger spinules at outer distal corner; medial armature consisting of two short spines; apical armature consisting of two spines and three geniculate setae, longest of which with spinules around geniculation and fused basally to naked accessory seta.

Mandibular palp two-segmented ( Fig. 3D View FIGURE 3 ); basis elongate with one lateral seta; endopod forming right angle with basis, with one inner, two subapical and two apical setae; all armature elements naked. Gnathobase with fine teeth distally and one minutely pinnate seta at dorsal corner.

Maxillule ( Fig. 3E View FIGURE 3 ) with praecoxal arthrite bearing seven elements around distal margin. Coxal endite with two naked spines. Basis with rami entirely incorporated, forming one-segmented elongate palp with eight naked setae.

Maxilla ( Fig. 3F View FIGURE 3 ). Syncoxa with two slender coxal endites; proximal and distal endites each with basally fused spine and two and one additional setae, respectively. Allobasis drawn out into long slender claw with one accessory seta. Endopod one-segmented; with three setae. All elements naked.

Maxilliped ( Fig. 3G View FIGURE 3 ). Syncoxa small and unarmed. Basis elongate and unarmed. Endopod with minute accessory seta and slightly curved claw, bearing subterminal spinule along medial margin and minute spiniform process halfway along outer margin.

P1 ( Fig. 4A View FIGURE 4 ). Intercoxal sclerite wide and subrectangular. Praecoxa triangular and naked. Coxa without ornamentation. Basis with spinular row near base of endopod and along outer margin; anterior surface with a pore and a small spine near medial margin. Exopod three-segmented; all segments with spinules around outer margin, those of exp-3 shortest; 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 about 5 times longer than wide, and 1.3 times longer than exopod; with a serrate inner seta in proximal half, and three groups of sparse spinules along outer margin; enp-2 slightly longer than wide, distal margin with a short unipinnate outer spine and a long geniculate inner claw.

P2–P4 ( Fig. 4B–D View FIGURE 4 ) intercoxal sclerites naked, with concave distal margin. Praecoxae small and naked, represented by triangular sclerite. Coxae squarish and without ornamentation. Bases smaller than coxae, with a spinular row near base of endopod (P3–P4) and at outer distal corner (P2–P4); anterior surface with a pore near articulation with coxa; outer basal seta absent (P2), plumose (P3) or naked (P4). Exopods three-segmented; segments with spinular ornamentation as figured; all elements uni- or bipinnate; hyaline frills of exp-1 and -2 well developed; exp-2 with lateral pore halfway down inner margin length. Endopods two-segmented, with enp-1 distinctly longer than enp-2; P2–P4 enp-1 about 1.9, 1.9 and 3.3 times longer than their respective distal segments, with few coarse spinules as figured. P2 enp-2 with a long, apically serrate, posteriorly directed seta near proximal inner margin. P2–P3 enp-2 with a long bipinnate seta terminally. P4 enp-2 minute, with a basally fused, apically serrate seta, and a long bipinnate seta at outer distal corner. Spine and seta formula as follows:

Fifth legs ( Figs 5C View FIGURE 5 ; 6C View FIGURE 6 ) closely set together but not touching medially. Baseoendopod and exopod fused, forming a rectangular plate with anterior surface pore; distal margin with three pinnate elements, middle one half the length of outer one, inner one spiniform; outer basal seta long and plumose.

Genital field ( Figs 5C View FIGURE 5 ; 6C View FIGURE 6 ) positioned near anterior margin of genital double-somite. Genital apertures fused forming median slit; closed off by fused P6 forming common operculum with one minute dentiform process on either side; copulatory pore located midventrally; seminal receptacles difficult to discern.

Description of male. Total body length from tip of rostrum to posterior margin of caudal rami 240–280 μm (mean = 255 μm; n = 10). Maximum width 35 μm measured at cephalothorax. Body ornamentation ( Fig. 6B View FIGURE 6 ) essentially as in female. Sexual dimorphism in antennule, urosomal segmentation, P5 and P6.

Antennule ( Fig. 5D View FIGURE 5 ) nine-segmented, haplocer; geniculation between segments 7 and 8. Segment 2 longest and about 2.5 times longer than wide; segment 4 an incomplete sclerite with 1 modified (fused at base) and 1 tiny element; segment 5 with three setae plus long aesthetasc (L: 37 μm) fused basally to a small slender seta; segment 6 with a spinulose spine and long distal seta; segment 7 with four modified spines and two setae; segment 8 with three basally fused, modified spines; 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-[2 + (1 + ae)], 6-[1 + 1 modified], 7-[2 + 4 modified], 8-[1 + 3 modified], 9-[7 + acrothek]. Acrothek consisting of short aesthetasc (L: 14 μm) fused basally to two slender setae.

P5 ( Fig. 6A View FIGURE 6 ) with anterior surface pore with armature as in female but all elements distinctly shorter and more spiniform; inner element also shorter than outer one (instead of equally long as in the ♀). Outer basal seta naked.

Sixth legs ( Fig. 6A View FIGURE 6 ) asymmetrical, with smallest P6 closing off functional gonopore; each with a long naked outer seta and a short bipinnate inner spine.

Etymology. The specific epithet (a noun in the genitive case) is derived from the geographical name Anatolia ( Asia Minor) which represents the Asian part of Türkiye, the region where the specimens were collected.

Remarks. Arenopontia anatolica sp. nov. belongs to a complex of closely related species, including A. subterranea , A. problematica and A. adriatica sp. nov. (see Remarks under the latter species). It can be differentiated from the congeners of this group by the short P1 endopod, enp-1 being only five times as long as wide and 1.3 times the length of the exopod ( Table 1 View TABLE 1 ).

According to Sak (2004) the species assumes an almost continuous distribution along the Turkish Black Sea coast from the Bulgarian border to Georgia with confirmed records from Iğneada and Kastro (Kırklareli Province), Karasu and Ağva (Kocaeli Province), Caferiye (Sakarya Province), Terme and Omtel (Samsun Province), and Kuzguncuk (Trabzon Province). The species was also recorded from Ören along the Aegean Sea coast (Balıkesir Province) ( Sak 2004). Noodt’s (1955c) record of A. subterranea from a sandy beach near the Bosporus (Black Sea coast) almost certainly refers to A. anatolica sp. nov. According to Sak (2004), the Black Sea material identified by Marinov (1971) as A. subterranea is very similar to A. anatolica sp. nov., however, obstacles remain to confirm conspecificity (see below).