Cyzicus Audouin, 1837

Schwentner, Martin, Rabet, Nicolas, Richter, Stefan, Giribet, Gonzalo, Padhye, Sameer, Cart, Jean- François, Bonillo, Céline & Rogers, D. Christopher, 2020, Pseudosesarma crassimanum, Zoological Studies (Zool. Stud.) 59 (44), pp. 1-23 : 14

Cyzicus Audouin, 1837

= Caenestheriella Daday, 1914: 106 fide Margalef, 1953, fide Straškraba 1965b

= Caenestheria Daday, 1914: 53 pro partim

Diagnosis: Populations composed of males and females (except C. gynecius which is only composed of hermaphrodites); amplexus is venter to venter. Rostrum subtriangular (usually females) to subquadrate (usually males), depending on age and gender. Angle between rostrum and frons 160° to 180°. Occipital notch either deep and narrow, often closed or very shallow, or absent. Occipital condyle either conical, subacute, length subequal to basal width or low, rounded, length half or less basal width. Rostral spine generally absent (present in C. australis ). Carapace valve length ~1.3x valve breadth (umbone to margin). Carapace growth line intervals smooth or ornamented (scarring from algae often mistaken for ornamentation). Carapace typically dark brown, occasionally black, or with yellow markings, often with setae. Clasper endopod (= movable finger) apically unarmed, or with a few setae, apical margin crenulate at most, but never with claw-like seta or scales. Endite IV broadly transverse to cylindrical, bearing a dense, apical field of short spiniform setae. Thoracic segments smooth or with a central dorsoposterior projection and/or set of spines or setae. Eggs attaching to prolonged exopods of thoracopods IX and X. Thoracopod exopods lacking a triangular lamina. Telson posteriolateral spine rows confluent dorsally, with confluence not projecting. Each row has from 10 to 30 spines depending on species. Caudal filament (= telsonic filament) originating between spine rows at fifth, sixth, or seventh spines from confluence. Caudal filament borne or not on projecting mound. Cercopods arcuate, occasionally sinuate, or straight with distal fourth to third bent dorsally. Cercopod with medial longitudinal setal row on proximal 40–60%. Setae plumose and either long or short. Setal row terminates with single spine. Cercopod with subapical, dorsal cirrus, extending from 60–40% of cercopod length. Eggs smooth, unornamented.

Comments: The type species is Limnadia tetracera Krynicki, 1830 (now recognized as C. tetracerus ) fixed by monotypy. Currently, we recognize about 25 species in this genus ( Rogers 2020). At this time the genus is morphologically defined based upon the family characters and the clasper endopod apically unarmed, or with apical margin crenulate at most. Further molecular and morphological analyses are needed to clarify relationships among the members of this genus. The genera Caenestheria and Caenestheriella are not supported in our analysis. Indeed, one species in our analysis that was formerly attributed to Caenestheriella , Cyzicus setosus , appears to be to be conspecific with Cyzicus californicus .