Karaytugia, Huys, Rony & Mu, Fanghong, 2021

Karaytugia gen. nov.

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Kuru & Karaytuğ (2015) described a new species, Parastenhelia aydini , from a Turkish beach in the Eastern Mediterranean and considered it morphologically most similar to Pa. spinosa . The authors refer to their unpublished observations but it is not clear which “population” they identified as Pa. spinosa . They differentiated Pa. aydini from the latter by the combination of the following characters: (a) ♀ antennule 9-segmented; (b) spinular rows near outer margin of P1–P4 bases significantly reduced; (c) P4 enp-3 with four setae in both sexes; (d) ornamentation of endopodal and exopodal setae of ♀ P5 different; (e) caudal ramus seta V of ♀ not swollen near the base; (f) modified element on the seventh segment of ♂ antennule not present; (g) apophysis on ♂ P3 enp-3 notched; and (h) ♂ P5 exopod 2-segmented, five setae in total .

Unique characters displayed by Pa. aydini include (a) the modification of the endopodal claw on the maxilliped; the distal half does not taper to a sharp tip as in other members of the family, forming instead a spatulate structure fringed with a series of densely arranged serrations around the inner margin and rounded apex; (b) P1 exp-3 with one very long naked seta and three claws of different lengths, the longest one being 0.8 times the length of exp-2; (c) P1 enp-2 claws radically divergent in size, with large one nearly three times longer than short one; (d) inner seta of P2–P3 enp-1 reduced; (e) spinous apophysis on ♂ P3 endopod with foot-shaped tip; and (f) ♂ P5 exopod 2-segmented, with one very long outer seta on exp-1 and four elements on exp-2; the only other species in the Parastenheliidae that display a 2-segmented exopod are Parastenhelia willemvervoorti sp. nov. and Johnwellsia bipartita gen. et sp. nov. which have six short elements, and one spine and two setae, respectively, on exp-2. Based on this combination of apomorphic character states, Pa. aydini is her fixed as the type species of a new genus, Karaytugia gen. nov.

Diagnosis. Parastenheliidae . Sexual dimorphism in antennule, P2–P3 endopods, P5–P6 and urosomal segmentation. Body subcylindrical, short; posterior margin of cephalothorax and somites bearing P2–P5 with plain hyaline frills; remaining urosomites (except anal somite) with serrate hyaline frills. Rostrum defined at base, of moderate size, reaching to about halfway second segment of antennule; elongate triangular. Anal operculum semicircular, bordered with fine spinules. Caudal ramus wider than long, with conspicuous spinular ornamentation; with seven setae, setae IV– V not basally inflated in ♀ .

Antennule elongate and 9-segmented in ♀, segment 1 not elongate, segments 7–8 shortest, with aesthetascs on segments 4 and 9; haplocer and 11-segmented in ♂, with geniculation between segments 7 and 8, segment 5 swollen and with aesthetasc; segmental homologies in ♂: I, II– VIII, IX – XII, XIII, XIV – XVII, XVIII, XIX – XX, XXI – XXII, XXIII, XXIV – XXV, XXVI – XXVIII. Antenna not sexually dimorphic; proximal endopodal segment largely separated from basis, with pinnate seta on abexopodal margin; exopod 2-segmented, proximal segment with two setae, distal segment with two lateral and three apical elements; distal endopodal segment without penicillate elements. Mandible with three elements on basis; endopod with eight setae; exopod 1-segmented, with two setae. Maxillulary coxal epipodite represented by one seta. Maxilla with three endites on syncoxa; endopod discrete, with three setae. Maxilliped with two setae on syncoxa; basis with two setae and longitudinal spinular row on palmar margin; endopod represented by conspicuously serrated claw, accompanied by three accessory setae .

P1 inner basal spine not sexually dimorphic. P1 exopod 3-segmented; exp-2 much longer than others, nearly three times as long as exp-1 and about half as long as enp-1, with short inner seta; exp-3 small, with two pinnate spines, one geniculate seta and one naked seta. P1 endopod 2-segmented; enp-1 elongate, about 1.5 times length of exopod, with short, proximally inserted, pinnate inner seta, segment margins without area of reduced chitinization; enp-2 very small, with one naked minute seta and two dentate claws. P2–P4 rami 3-segmented; inner seta of P2–P3 exp-1 reduced in size, absent in P4. P2–P3 endopods ♂ 3-segmented. P2 slightly more robust in ♂. P3 endopod ♂ without inner setae ( vs two in ♀) on enp-3 and outer spine modified into apically truncated spinous apophysis. Armature formula of P2–P4 as follows:

P 5 ♀ endopodal lobe with five setae, outermost well developed, innermost shortest; inner margin without transverse striae. P 5 ♀ exopod elongate, with six elements. P 5 ♂ endopodal lobe with two elements, outer one shortest; exopod 2-segmented, with one long outer seta on exp-1 and four elements on exp-2. Vestigial P 6 ♀ represented by three minute setae. P 6 ♂ with three setae.

Etymology. The genus name is dedicated to Prof. Süphan Karaytuğ ( Mersin University, Turkey), in recognition of his contributions to the harpacticoid fauna of Turkey, and under whose mentorship the next generation of harpacticoid experts in his home country emerged. Gender: feminine.

Type and only species. Parastenhelia aydini Kuru & Karaytuğ, 2015 = Karaytugia aydini ( Kuru & Karaytuğ, 2015) comb. nov. (by original designation herein).