Order CUMACEA Krøyer, 1846

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Order CUMACEA Krøyer, 1846

Compiler and date details

Helen E. Stoddart & James K. Lowry

Introduction

Cumaceans are small benthic peracaridans usually found in soft sediments. They are mainly deposit-feeders. There are no parasitic forms. They have an adult male swimming stage which is considered to be a searching stage for reproductively mature females. Family level classification is difficult. During their taxonomic history cumaceans have been divided into between four and 26 family level groups. There are currently eight recognised families of which six are reported from Australian waters. As in the Amphipoda,virtually nothing is known of the evolutionary history or phylogenetic relationships within the Cumacea (Gerken 2001). There are currently about 1250 described species of which 228 are known from Australian waters. Bodotriidae and Gynodiastylidae, the two largest Australian families, have about 82 species each. Although Australian cumaceans appear diverse at the generic level (39 genera), Cyclaspis (52 species) in the Bodotriidae and Litogynodiastylis (28 species) and Gynodiastylis (23 species) both in the Gynodiastylidae, make up nearly half of Australian species diversity.

Synopsis of Australian Cumacean Taxonomy

Our understanding of the Australian cumacean fauna has benefited greatly from the work of a small number of careful taxonomists who have described the overwhelming majority of the fauna. The first important worker was Zimmer (1914, 1921) who described 14 species from southern Australia. Between 1928 and 1953 Herbert Hale, in a series of 18 wonderfully crafted papers, described 142 cumacean species from southern Australian waters. Description of the fauna lay dormant until Bacescu (1990, 1991, 1992) described six species from the North West Shelf in the first work on cumaceans from northern Australian waters. Tafe & Greenwood (1996a, 1996b) then described 14 species from Moreton Bay, Queensland, further developing the northern fauna. Recently, Gerken (2001) published a major monograph revising the gynodiastylid component of the fauna and adding an additonal 38 species. These works have made the Australian cumacean fauna (currently 228 species) one of the best described and understood Australian peracaridan groups. The references listed below are the essential literature for the study of Australian cumacean taxonomy.

Diagnostic Descriptions of Families

If males and females are considered together, then it is not possible to diagnose cumacean families. Using males only it is possible to diagnose all families except for the Bodotriidae and Nannastacidae which will not separate. Using females all families can be distinguished.

The diagnostic descriptions are based on diagnoses generated from a DELTA (Dallwitz et al. 1993, 1998) database of cumacean higher level taxa. Each description contains the complete set of diagnostic characters for each cumacean higher level taxon. Characters in bold text refer to the unique combination of character states which will define each taxon against all others at that rank.

Phylogeny
The monophyly of the order was confirmed by the phylogenetic analysis of Gerken et al. (2021).

Diagnosis

Carapace present; thoracomere 1–3 fused to head (bearing maxillipeds). Eyes sessile. Antenna 1 typically biramous (inner ramus reduced). Maxillipeds with basal and ischial endites. Thoracopods 4–8 (pereopods 1–7) biramous, coxae not forming plates. Pleopods, 5 pairs, usually absent in female, variously reduced in male. Uropods, 1 pair. Young released from brood pouch as mancae. Male usually with a pair of tubercles on sternum of pereonite 5; female gonopores on pereonite 3.