Genus Arenopontia Kunz, 1937

Diagnosis (adapted from Sak et al. 2008). Arenopontiidae . Urosomites without conspicuous surface ornamentation. Anal somite without paired dorsolateral spinous processes.Anal operculum not modified. Hyaline frills of abdominal somites with rectangular digitate lappets. Caudal ramus with dorsolateral spur or raised spinular row near medial margin. P1 exopod three-segmented; exp-1 with outer spine; exp-2 without outer element; exp-3 with two spines, one outer distal geniculate seta and one inner distal penicillate seta. P1 endopod prehensile, longer than exopod; enp-1 elongate and distinctly longer than exopod; enp-2 with one outer distal spine and one inner distal geniculate claw. P2–P3 endopods two-segmented. P3 endopod with outer distal element not defined at base or absent. P4 endopod with well developed outer distal element. Armature formula as follows:

P3 endopod ♂ not sexually dimorphic, two-segmented. P5 with outer basal seta and three–four discrete elements; innermost one distinctly smaller in ♂. P 6 ♂ with one–two seta(e).

Type species. Arenopontia subterranea Kunz, 1937 [by monotypy].

Other species. A. problematica Masry, 1970; A. nesaie Cottarelli, 1975; A. riedli Lindgren, 1976; A. anatolica sp. nov.; A. adriatica sp. nov.; A. basibuyuki sp. nov.; A. gunduzi sp. nov.; A. syltensis sp. nov.

Species inquirenda. A. pontica Apostolov, 1969 .

Taxa of doubtful identity. Arenopontia subterranea Kunz, 1937 sensu Chappuis (1954a); A. subterranea Kunz, 1937 sensu Chappuis (1954b); A. subterranea Kunz, 1937 sensu Şerban (1959); A. subterranea Kunz, 1937 sensu Rao & Ganapati (1969); A. subterranea Kunz, 1937 sensu Marinov (1971); A. subterranea Kunz, 1937 sensu Apostolov (1973); A. subterranea Kunz, 1937 sensu Cottarelli (1975); A. subterranea Kunz, 1937 sensu Lindgren (1976); A. subterranea Kunz, 1937 sensu Arlt (1983); A. subterranea Kunz, 1937 sensu Rao (1991); A. nesaie Cottarelli, 1975 sensu Mitwally & Montagna (2001) .

Nomina nuda . “ Arenopontia subterranea Kunz, 1937 ?” sensu Şerban & Eitel-Lang (1957); Arenopontia ciplaki Sak, 2004; A. daltonae Sak, 2004 .

Etymology. The generic name is derived from the Latin arena, meaning sand, and the Greek πόνΤΟΣ, meaning sea. Gender: feminine.

a Based on Kunz (1937: Abb. 9–Fig. 43).

b According to Kunz (1937) and Masry (1970) the P6 is represented by a minute plate bearing three elements but it is conceivable that their claims are based on observational errors.

c Based on Sak’s (2004) redescription and present account.

d Masry (1970) erroneously claimed that there are two distal elements on P2–P3 enp-2.

The nine species recognized here as valid can be assigned to two groups based on the ornamentation of the proximal endopodal segment of P1 (Table 1). In Group I the outer margin of P1 enp-1 shows three sets of (typically two, occasionally three) spinules which are more or less evenly distributed along the length of the segment (e.g. Figs 1A; 4A; 12A; 20A). In Group II the ornamentation on P1 enp-1 consists of a single prominent spinule positioned near the outer distal corner of the segment (e.g. Figs 10A; 15A). Members of Group I are also characterized by the presence of 0–1 spatulate element(s) on the apical segment of the antennule in both sexes, and two elements on the male P6. In Group II the terminal antennulary segment displays two spatulate setae and the male sixth legs exhibit only one seta. None of the three characters employed to define these groups is known to show variability. Although the phylogenetic significance of this division cannot be tested at present it serves as a useful working model to discuss morphological relationships of taxa of doubtful identity, particularly when only few illustrations (e.g. P1) are available.