Cyzicus Audouin, 1837

Rogers, D. Christopher, 2020, Spinicaudata Catalogus (Crustacea: Branchiopoda)., Zoological Studies 59 (45), pp. 1-44 : 17-18

Cyzicus Audouin, 1837

= Estheria Rüppell in Strauss-Durchheim, 1837 (pro partim), nomen praeoccupatum = Isaura Joly, 1842 nomen praeoccupatum = Caenestheriella Daday, 1914: 106 , fide Margalef,

1953, fide Straškraba 1965b

= Caenestheria Daday, 1914: 53 (pro partim)

= Bairdestheria Raymond, 1946

= Opsipolygrapta Novojilov, 1954 (pro partim)

Diagnosis: (From Schwentner et al. 2020a). Populations composed of males and females (except C. gynecia 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, very shallow or absent. Occipital condyle conical, subacute, length subequal to basal width. Rostral spine generally absents. 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 apically unarmed, or with a few setae, apical margin crenulate at most. 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 posterior margin posteriolateral spine rows confluent dorsally, with confluence not projecting. Each row has from 10 to 30 spines depending on species. Caudal 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: Limnadia tetracerus Krynicki, 1830 is the type species monotypy (Auduoin 1837). Caenestheriella was treated as a junior synonym based on morphological and developmental grounds by Margelef (1953), Straškraba (1965b), Wiltshire (1973), Forró and Brtek (1984), Sassaman (1995), Smith and Gola (2001) and Orridge (2011). Molecular results support this move ( Schwentner et al. 2015 2020a). The character for separating the two genera was the form of the rostrum which was triangular in in Caenestheriella , but quadrate in at least male Cyzicus ( Daday, 1913a) . However, Wiltshire (1973) demonstrated that this was a matter of development at least in Nearctic species; younger animals have a triangular rostrum and older animals a quadrate rostrum, with both forms sexually reproductive.

Tiwari (1966) moved Cyzicus indicus and C. boysii into the fossil genus Baidestheria Raymond, 1946 . Baidestheria species are diagnosed as having the carapace intervals bearing radial striae as opposed to punctae. Rogers and Padhye (2015) point out that carapace fine characters may not be diagnostic at genus level, as they are affected by epibiontic algal growth and probably by nutrition.

García and Pereira (2003) state that the Cyzicidae has not been reported from South America; Daday (1914) reported a specimen of C. jonesi from southern South America, and two Cyzicus nomina dubia were described from Brazil, both based on empty carapaces, so their actual placement is questionable.

Many Cyzicus taxa from Africa and Eurasia may be moved to Ozesthehria upon re-examination.

Attributed Species