Eulimnadia Packard, 1874

Rogers, D. Christopher, 2020, Spinicaudata Catalogus (Crustacea: Branchiopoda)., Zoological Studies 59 (45), pp. 1-44 : 5-6

Eulimnadia Packard, 1874

= Eulimadia (in error). Sars, 1895, 1896a b

= Limnadia Webb & Bell, 1979 ; Brtek 1997; Naganawa 2001a b

= Uenia Naganawa, 2001b

Diagnosis: (modified from Rogers et al. 2012) Populations composed of males and hermaphrodites (except E. agassizii which is only composed of hermaphrodites); amplexus is venter to venter. Rostrum variable, blunt to acute, long or short. Angle between rostrum and frons 80° to 100°. Occipital notch occipital condyle absents. Pedunculate frontal organ length approximately 1.55x distance of organ from ocular tubercle. Carapace dorsal margin smooth, lacking carinae, hinge line arcuate, rarely sinuate. Carapace surface between growth lines smooth. Umbone absent. Carapace occasionally pigmented. Muscle scar angle from 0° to 90° from normal. Clasper endopods each bearing an apical suctorial organ. Endite IV may be broadly transverse or bear dense apical field of short setae, or a few long setae or spines. Thoracic segments smooth or with dorsoposterior ridge rimmed with spines or setae. Eggs attaching to prolonged exopods of thoracopods VII and VIII or VIII, VIII to IX or XII, IX and X, X and XI, or XI and XII. Telson with a subcercopodal, posteriorly directed spiniform projection on ventroposterior angle, anteriad of cercopod base. Telson posterior margin posteriolateral spine rows confluent dorsally, with confluence not projecting. Each row has from 6 to 22 spines. Caudal filament originating between spine rows at second, third, fourth, fifth, or seventh spines from confluence. Caudal filament borne on projecting mound. Cercopods arcuate, occasionally sinuate. Cercopod with medial longitudinal setal row on proximal 75 to 80%. Setae plumose and long. Setal row terminates with single spine. Cercopod with subapical, dorsal cirrus, extending from 5–30% of cercopod length. Eggs 170–250 μm in diameter. Shape spherical to subspherical or cylindrical to subcylindrical with one end larger than other. Eggs with large rectilinear polygonal depressions separated by ridges, occasionally with lamellar or setaform spines at polygon ridge line confluences ( Belk 1989; Martin 1989; Martin and Belk 1989; Rabet 2010).

Comments: No type species was designated by Packard (1874). The type for the genus is designated here as Limnadia agassizii . Important works on this genus include Belk (1989), Martin (1989), Martin and Belk (1989), Rabet (2010), Rogers et al. (2012), and Marinone et al. (2016). Species are so far only reliably separated by egg morphology ( Belk 1989; Martin and Belk 1989; Rabet 2010; Rogers et al. 2012; Padhye and Kulkarni 2017), including internal characters ( Rabet et al. 2012). However, external characters in sediment collected eggs may be affected by the environment ( Rabet et al. 2014).

Webb and Bell (1979), Brtek (1997) and Naganawa (2001a b) all treated Eulimnadia under Limnadia , however morphological and molecular characters more than justify this genus as distinct ( Martin and Belk 1989; Rogers et al. 2012).

Reports of undescribed Eulimnadia from the Neotropical region are reviewed in Rogers et al. (2020). Eulimnadia victoriae Brady, 1916 is a Cyclestheria (Cyclestheridia) (fide Brendonck 1999). A single hermaphrodite specimen (lacking eggs) reported from Thailand ( Rogers et al. 2012) had a rostral spine. This is the only record of a rostral spine in Limnadiidae , and no other specimens have been found.

Attributed Species