Phreatipontia speluncae ( Cottarelli, Bruno & Venanzetti, 1994 ) Sak & Karaytuğ & Huys, 2024

Sak, Serdar, Karaytuğ, Süphan & Huys, Rony, 2024, Review of Neoleptastacus Nicholls, 1945 (Harpacticoida, Arenopontiidae), including an updated key to species and proposal of Phreatipontia gen. nov., Zootaxa 5525 (1), pp. 1-66 : 54-61

publication ID	https://doi.org/ 10.11646/zootaxa.5525.1.1
publication LSID	lsid:zoobank.org:pub:7F2F59B2-E0FB-4E17-BAF1-31228DB9428E
persistent identifier	https://treatment.plazi.org/id/627EC678-F753-FF83-FF4E-F89B789FFAAE
treatment provided by	Plazi
scientific name	Phreatipontia speluncae ( Cottarelli, Bruno & Venanzetti, 1994 )
status	comb. nov.

Treatment

Phreatipontia speluncae ( Cottarelli, Bruno & Venanzetti, 1994) comb. nov.

( Figs 16–19 View FIGURE 16 View FIGURE 17 View FIGURE 18 View FIGURE 19 )

Arenopontia (Neoleptastacus) speluncae Cottarelli, Bruno & Venanzetti, 1994 View in CoL

Neoleptastacus turcicus —nomen nudum by Sak (2004: 221)

Neoleptastacus speluncae ( Cottarelli, Bruno & Venanzetti, 1994) Sak et al. (2008: 412) Original View in CoL description. Cottarelli et al. (1994): 475 –480; Figs 2–3 View FIGURE 2 View FIGURE 3 .

Type locality. Italy, Lazio, Latina Province, Sperlonga, Tiberio beach; on the banks of a little stream that originates from a spring on the beach; interstitial water. Note that Cottarelli et al. (1994) also collected two females from a second locality in the Latina Province (S. Agostino beach in Gaeta ) but did not explicitly state where the female holotype originated from. Since they allocated numbers 2–13 to the paratypes (six ♀♀ and five ♂♂ in total were collected from Sperlonga, two ♀♀ from Gaeta) it appears rational to assume that number 1 was given to the holotype and that it came from Sperlonga. The etymology of the species name and the fact that additional drawings ( Figs 2–e View FIGURE 2 , 3–g View FIGURE 3 ) were presented of an atypical female of S. Agostino beach also seem to suggest that Sperlonga was the intended type locality .

Material examined. One ♀ (dissected on eight slides) and one ♂ (dissected one seven slides); 10 individuals in ethanol. All specimens collected from Ismailbeyli Village beach (41°02.198’ N; 38°56.901’ E) close to a small stream, Giresun (Giresun Province), northeastern Türkiye (Black Sea region); leg. S. Karaytuğ & S. Sak, 10 September 2002 GoogleMaps .

Body length. 394 μm (♀), 346 μm (♂) [Cottarelli ei al. 1994]; 356 μm (♀), 338 μm (♂) [present account].

Redescription of female. Total body length from tip of rostrum to posterior margin of caudal rami 356 μm (n = 1). Cephalothorax maximum width 42 μm measured at posterior margin. Maximum body width 47 μm, measured at P5-bearing somite. Body ( Fig. 16A, B View FIGURE 16 ) slender and cylindrical without clear distinction between prosome and urosome. Sensillar pattern on body as figured. Hyaline frills of thoracic somites weakly developed and plain; those of genital double-somite and free abdominal somites well developed and consisting of rectangular digitate lappets that taper towards their distal margins ( Figs 16A–B View FIGURE 16 ; 19A View FIGURE 19 ). Somites connected by well-developed intersomitic membranes. Genital double-somite slightly longer than wide (measured in dorsal aspect); with two ventral pores ( Fig. 19A View FIGURE 19 ). Anal somite ( Figs 16C, D View FIGURE 16 ; 19A View FIGURE 19 ) with two dorsal and four lateral pores. Anal frill triradiate, minutely incised (giving a spinulose appearance); anal operculum virtually straight, without ornamentation.

Caudal rami ( Figs 16C, D View FIGURE 16 ; 19A View FIGURE 19 ) about 3.4 times longer than wide (measured in dorsal view from anterior margin to apex of spinous process), distinctly tapering posteriorly; outer and inner margins slightly convex; with two ventral pores in proximal third and two lateral pores near insertion of seta III; terminal spinous process slightly recurved dorsally; no spinular ornamentation discernible. Armature consisting of seven setae; seta I small; setae II and III (displaced to dorsal surface) long and naked; seta IV short, located between seta V and posterior spinous process, with long outer spinule; seta V with proximal fracture plane; seta VI small, naked and located at inner distal corner; seta VII spatulate and tri-articulate at base.

Rostrum ( Fig. 16A View FIGURE 16 ) small, subtriangular, tapering distally; with two delicate sensilla.

Antennule ( Fig. 17C View FIGURE 17 ) long and slender, 6-segmented. Segment 1 with small seta near anterodistal margin. Segment 2 longest, about 2.5 times longer than wide. Segment 4 with long aesthetasc (L: 29 μm) fused at base with seta. Distal segment with eight setae (none of them spatulate) and apical acrothek consisting of short aesthetasc (L: 13 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-[8 + acrothek].

Antenna ( Fig. 17D View FIGURE 17 ). Coxa small, without ornamentation (not figured). Basis and proximal endopodal segment completely separated. Basis with few spinules along exopodal margin and with oblique spinular row near base of exopod. Exopod one-segmented and elongate, with a naked apical seta (about 1.4 times longer than exopod). Free endopodal segment with transverse spinular row distally; medial armature consisting of two short spines (indicated by arrows in Fig. 17D View FIGURE 17 ); apical armature consisting of two naked spines and three geniculate setae, longest of which with spinules around geniculation and fused basally to naked accessory seta.

Mandible, maxillule, maxilla and maxilliped as in P. phreatica .

P1 ( Fig. 18A View FIGURE 18 ). Intercoxal sclerite wide, naked and subrectangular, with concave ventral margin. Praecoxa small, triangular and naked. Coxa wider than long, without ornamentation. Basis with spinular row near base of endopod; anterior surface with a small setiform spine near medial margin and one pore near articulation with coxa. Exopod three-segmented; all segments with several spinules around outer margin; exp-1 about as long as exp-3, with naked outer spine; exp-2 without outer element; exp-3 with short naked outer spine, and a longer naked spine and two geniculate setae distally. Endopod two-segmented, not prehensile, slightly longer than exopod; enp-1 with virtually straight inner margin, about 1.5 times longer than enp-2, with a serrate seta arising from about halfway down inner margin and two sets of two spinules along outer margin; enp-2 without spinules, distal margin with two geniculate setae, outermost of which shortest.

P2–P4 ( Fig. 18B–D View FIGURE 18 ). Intercoxal sclerite naked (P2–P4), rectangular (P2) or squarish (P3–P4) with deeply concave ventral margins. Praecoxae triangular, small and naked. Coxae squarish (P3) or slightly wider than long (P2, P4) and without ornamentation. Bases smaller than coxae, with a spinular row near base of endopod (P2–P3) and a few spinules around outer corner in P2 and P4; anterior surface with a pore in P3-P4; outer basal seta absent in P2, naked in P3–P4. Exopods three-segmented; segments with coarse spinular ornamentation along outer margin; outer spine of exp-1 and exp-2 naked; exp-3 with an outer unipinnate spine and two bipinnate setae distally, P4 exp-3 with additional serrate seta on inner margin; P4 exp-2 only marginally longer than exp-1. Endopods two-segmented; P2–P4 enp-1 unarmed, about 1.2, 1.5, and 4.2 times longer than their respective distal segments, with few coarse spinules along outer margin as figured, but without ornamentation along inner margin; P2–P3 enp-2 with few spinules around distal margin; P2 enp-2 with long, apically serrate, backwardly directed seta near proximal margin and one unipinnate setae apically; P3 enp-2 with long, bipinnate apically; distal margin of P4 enp-2 with long, distally serrate and basally fused, inner seta, and shorter unipinnate, outer seta. Spine and seta formula as follows:

Exopod Endopod

P2 0.0.021 0.110

P3 0.0.021 0.010

P4 0.0.121 0.020

Fifth legs ( Fig. 19A View FIGURE 19 ) closely set together, almost touching medially. Baseoendopod and exopod fused, forming a subrectangular plate with straight distal margin; with one pore on anterior surface; inner distal corner with long, bipinnate spinous process (homologous to inner spine); distal margin with long naked outer seta and two short equally long, bipinnate spines; outer basal seta long and plumose.

Sixth legs vestigial, forming opercula closing off genital apertures.

Redescription of male. Total body length from tip of rostrum to posterior margin of caudal rami 338 µm (n = 1). Body ornamentation essentially as in female ( Fig. 17A View FIGURE 17 ). Sexual dimorphism in antennule, genital segmentation, P5, and P6. Spermatophore length approximately 70 μm.

Antennule ( Fig. 17B View FIGURE 17 ) 8-segmented, haplocer; geniculation between segments 6 and 7. Segment 1 with a naked seta; segment 2 longest and about 2.7 times longer than wide, with one plumose and seven naked setae; segment 3 with four setae; segment 4 an incomplete sclerite with two setae; segment 5 with four setae, one pinnate spine and a long aesthetasc (43 µm) fused basally to a slender seta; segments 6–7 with one seta each; distal segment with seven setae (none of which spatulate) and apical acrothek consisting of short aesthetasc (16 µm) fused basally to two slender setae. Armature formula: 1-[1], 2-[7 + 1 plumose], 3-[4], 4-[2], 5-[4 + (1 + ae)], 6-[1], 7-[1], 8-[7 + acrothek].

P5 ( Fig. 19B View FIGURE 19 ) essentially as in female but inner spinous process slightly more slender.

Sixth legs ( Fig. 19B View FIGURE 19 ) asymmetrical, with smallest P6 closing off functional gonopore; each with a long outer plumose seta and a shorter inner bipinnate seta.

Remarks. The report of an inner seta on P3 exp-2 by Cottarelli et al. (1994) is extremely doubtful and requires confirmation. No other member in the family Arenopontiidae displays an inner seta on this segment. Our specimens from the Black Sea agree in virtually all other morphological aspects with Cottarelli et al. ’s (1994) original description, adding further credence to the notion that their illustration of P3 is based on an observational error. The presence of an outer basal seta on P2 (their Fig. 3–e View FIGURE 3 ), their statement that the somitic hyaline frills are plain, and the absence of spinular ornamentation on the spinous process of P5 are also questionable and require further examination.

Cottarelli et al. (1994) did not observe any variability among the individuals from Sperlonga but illustrated the P5 and caudal ramus of a female from S. Agostino beach without further comment. The fifth leg of the latter deviates from that of the holotype in the shorter spinous process, the longer outer marginal seta (extending well beyond the process) and the general appearance of the two medial elements which are unequal in length and setiform in shape. The dorsal view of the caudal ramus is difficult to compare with the holotype since it was only illustrated in lateral aspect for the latter.

The two described species of Phreatipontia gen. nov. are morphologically very similar. The type species, P. speluncae comb. nov., can primarily be differentiated from P. phreatica comb. nov. by morphometric differences in the caudal rami and swimming legs. The exopodal segments of P2–P3 are distinctly more slender and longer in the latter, P2 enp-2 is markedly shorter (enp-1:enp-2 length ratio 1.6 vs 1.2) while P4 enp-1 is longer (enp-1:enp-2 length ratio 5.8 vs 4.2). The caudal rami are generally more slender and longer (L:W ratio 3.9 vs 3.4) in P. phreatica comb. nov. while the dorsal seta VII is more foliaceous in P. speluncae comb. nov.

In addition to the type locality, P. speluncae comb. nov. was also obtained in interstitial freshwater of S. Agostino beach (Gaeta, Latina Province, Lazio) on the banks of a little stream fed by a spring in Grotta del Serpente ( Cottarelli et al. 1994) and from the mouths of the Fiora River and Valfragida Stream, in the Viterbo Province (Lazio) ( Cottarelli et al. 1998; Berera 2000). Cottarelli & Berera (2004) also recorded it from the banks of the Fiora River near Montalto di Castro. Our material extends its distribution further into the Black Sea basin. Cottarelli et al. (1994) suggested that the species may be restricted to fresh or slightly brackish water but admitted that more data are needed before this can be corroborated. It is conceivable that P. speluncae comb. nov. (and P. phreatica comb. nov.) is in the process of colonizing continental subterranean waters ( Bruno et al. 1998). A third species, apparently close to P. speluncae comb. nov. and still under study, was discovered in freshwater habitats in Greece ( Bruno et al. 1998; Bruno & Cottarelli 1999).

Concluding remarks

Neoleptastacus is by far the most speciose genus in the family Arenopontiidae , currently including 24 valid species. Species identification is hampered by the fact that many members are only known from the type locality or a single record, have not been adequately described, or are part of cryptic species complexes (e.g. gussoae -subgroup) which are difficult to unravel.There is little doubt that some species have repeatedly been misidentified (e.g. N. secundus and N. indicus ) while others have mistakenly been treated as conspecific, leading to the misconception that they assume amphi-Pacific or amphi-Panamanian distribution patterns. Although the present review has identified a number of close-knit species groups in Neoleptastacus , the relationships between them are as yet not fully understood. A forthcoming phylogenetic analysis including all arenopontiid taxa will assess whether some or all of these groups may be accorded generic status or merely reflect diversification within the genus. This analysis will necessarily assess the phylogenetic significance of previously underrated characters such as male antennule morphology (position of geniculation), presence/absence of a middorsal process on the anal operculum and spinulation patterns on the caudal ramus. Some characters may turn out to be potential apomorphies for particular species-(sub)groups such as the presence of a medial spur on caudal ramus in the gussoae -subgroup, the presence of paired processes on the anal somite ( acanthus -group) or the fusion of the outer distal spine of P3 enp-2 ( spinicaudatus -group and others?). Others such as the presence of abdominal integumental patterns ( ornamentus -subgroup and N. clasingi ) or the shortening of the inner subdistal seta of P4 exp-3 ( N. chaufriassei and N. africanus ) are clearly the result of convergence that further complicate analysis of character state evolution in the genus and the family.