Eulimnadia, Packard, 1874

Timms, Brian V. & Rogers, D. Christopher, 2020, Fig. 5 in Paralbunea dayriti, Zoological Studies (Zool. Stud.) 59 (38), pp. 1-10 : 8-9

Characteristics of Eulimnadia globally

Literature descriptions of 34 Eulimnadia species were examined for the same features noted as in the Australian study: the form of the telson spiniform projection ( Fig. 4 ), the position of the spine at the distal end of the setal row on the cercopod, the number of antennomeres, the status of the medial surface of the clasper hand, and whether or not androdioecy is indicated by the sex ratio or better still by histology.

There is a large range in the position of the cercopod spine, from 60–90% of the cercopod length, with an average of 81% for the 34 species. According to Rogers et al. (2012) the range is 20–90%, but it seems Timms (2016a) did not encounter the most aberrant species in his survey. So this character is not as definitive outside of Australia, though with only a few exceptions the position is greater than 65% and for most near 80%. Thus this character is useful but not necessarily definitive.

There is also a much larger range for the number of second antennal antennomeres (5–17) globally. Two species, E. curvirostris Roen, 1952 and E. kobai Uéno, 1940 from China, are clearly outliers with 17 antennomeres, as the next highest number is 10. Although mentioned in the literature (e.g., Rogers et al. 2013; Reed et al. 2015) neither species has been studied since description. Without these two species the average is 7.8 antennomeres. So having ca eight antennomeres is a satisfactory guide to Eulimnadia but not necessarily definitive.

For about half (18) of the species in the survey, androdiocecy is indicated by sex ratios but only proved histologically for a few (such as E. texana, Weeks et al. 1997 ). There is no information for the remainder, but it should not be assumed they are gonochoristic. However, if sex ratios are the only guide then gonochoristic reproduction is indicated for E. indocylindrova , E. pulchra , E. santiaguensis , and E. agassizii . Of more importance in the form of amplexus, with single file being unique among all clam shrimp to the Paralimnadia / Limnadopsis clade.

Concerning a distinct hamulus on the male clasper medial surface, where males are known, not one Eulimnadia has a distinctly narrow protruding hamulus, though a couple have a sharp angle distally ( E. geayi , E. follisimilis ) and a few (10) have a moderate rounded protrusion distally. As in the Australian species this character is useful, but not necessarily definitive.

Figures

Fig. 4. Subcercopodal projection (and variation), left lateral view, among non-Australian Eulimnadia species. A, E. agassizii; B, E. astraova; C, E. brasiliensis; D, E. braueriana; E, E. chaperi; F, E. colombiensis; G, E. cylindrova; H and I, E. diversa; J and K, E. folisimilis; L, E. geayi; M, E. graniticola; N, E. michaeli; O, E. magdalensis; P, E. ovisimilis; Q, E. texana.