Interest in cryptic species has increased significantly with current progress in genetic methods. The large number of cryptic species suggests that the resolution of traditional morphological techniques may be insufficient for taxonomical research. However, some species now considered to be cryptic may, in fact, be designated pseudocryptic after close morphological examination. Thus the “cryptic or pseudocryptic” dilemma speaks to the resolution of morphological analysis and its utility for identifying species. We address this dilemma first by systematically reviewing data published from 1980 to 2013 on cryptic species of Copepoda and then by performing an in‐depth morphological study of the formerEurytemora affiniscomplex of cryptic species. Analyzing the published data showed that, in 5 of 24 revisions eligible for systematic review, cryptic species assignment was based solely on the genetic variation of forms without detailed morphological analysis to confirm the assignment. Therefore, some newly described cryptic species might be designated pseudocryptic under more detailed morphological analysis as happened withEurytemora affiniscomplex. Recent genetic analyses of the complex found high levels of heterogeneity without morphological differences; it is argued to be cryptic. However, next detailed morphological analyses allowed to describe a number of valid species. Our study, using deep statistical analyses usually not applied for new species describing, of this species complex confirmed considerable differences between former cryptic species. In particular, fluctuating asymmetry (FA), the random variation of left and right structures, was significantly different between forms and provided independent information about their status. Our work showed that multivariate statistical approaches, such as principal component analysis, can be powerful techniques for the morphological discrimination of cryptic taxons. Despite increasing cryptic species designations, morphological techniques have great potential in determining copepod taxonomy.

Eurytemora carolleeae sp. nov. (Crustacea: Copepoda: Calaniformes) is described from the Chesapeake Bay, USA. The new species belongs to the Atlantic clade of the Eurytemora affinis complex outlined by previously published molecular work but poorly characterized morphologically. To discriminate E. carolleeae we compare specimens from the Atlantic USA clade with specimens from the type population of E. affinis (Poppe, 1880) from the Elbe River Estuary (Germany), as well as with eight other European coastal populations. Several important morphological characters clearly separate the North American E. cf. affinis from the European clade that include both sexes: a large outside orientated dent on the mandible, and clearly observable seta segmentation in the caudal rami and swimming legs. Unlike E. affinis, the newly described species possesses wing-like outgrowths on the genital double-somite and a very small spine near the distal seta insertion point in P5 in females. In males, the specific characters include naked dorsal and ventral sides of the caudal rami, and a cylindrical shape of exopod on the left P5, in contrast to a triangular shape of the segment in E. affinis. The new species was also found in Canada (St. Lawrence Estuary) and as an invasive species in the Baltic Sea. Eurytemora carolleeae is possibly widely distributed along the North American Atlantic coast, as well as in inland waters from Great Lakes to Mexico.

Cyclopoid and calanoid copepod biodiversity in Indonesia