Subfamily Eumedoninae Dana, 1853

Ceratocarcinus longimanus [from Adams & White 1848]

Museums

Regional Maps

• Eumedonidae Dana, J.D. 1853. Crustacea of United States Exploring Expedition during the years 1838, 1839, 1840, 1841, 1942, under the command of Charles Wilkes, U.S.N., with atlas of 96 plates. C. Sherman Vol. 13 1395-1592 pp., 1 map. [1422].

  Type genus:

   Eumedonus H. Milne Edwards, 1834.
• Hapalonotinae Števčić, 2005.
• Rhabdonotini Stevcic, Z. 2011. Addition to the reclassification of brachyuran crabs (Crustacea: Decapoda: Brachyura). Part I. New taxa. Natura Croatica 20(1): 125–139.
• Ceratocarcininae Stevcic, Z., Castro, P. & Gore, R.H. 1988. Re-establishment of the family Eumedonidae Dana, 1853 (Crustacea: Brachyura). Journal of Natural History 22: 1301-1324 [1317].

  Type genus:

   Ceratocarcinus White, 1847.

Introduction

Eumedonines live symbiotically on and within echinoderms. Several records of their presence on sponges and soft corals require confirmation, and are probably a result of dislodgement from the hosts during collecting. Eumedonines can be relatively common on tropical reefs, but they are mostly small (typically around 1 cm carapace length), and their cryptic habits mean that they are seldom encountered or collected. Species are often, but not always, host specific. Of the 11 genera currently recognised, ten occur in Australian waters, with one, Zebridonus Chia, Ng & Castro, 1995, apparently indigenous to the Gulf of Carpentaria. In an important recent paper, Chia & Ng (1998) revised Ceratocarcinus White and Harrovia Adams & White, created three new genera, and provided keys to all taxa. Ng & Clark (2000) reviewed adult and larval characters of the Eumedoninae and made a strong argument for its inclusion as a subfamily of the Pilumnidae, although earlier it had been treated as a family in its own right (Stevcic et al. 1988).

Diagnosis

Carapace subpentagonal or subhexagonal; nearly flat, sometimes bearing pointed tubercules; regions more or less indistinct; junction between antero- and posterolateral margins usually well marked, often with a spine. Front projecting, bilobed or quadrilobed, rarely emarginate. Orbits circular, small, well defined; orbital hiatus filled by basal antennal segment. Antennae small, basal antennal article largest; flagellum short. Epistome wide, short; buccal cavity quadrangular, completely covered by third maxillipeds. Chelipeds moderate sized, subequal; ischio-meral suture fused, but distinct; chelipeds and walking legs often armed with spines or cusps. Walking legs with dactylo-propodal articulation formed by rounded prolongation of propodal lateral margin sliding against and beneath proximal projecting button on lateral margin of dactylus. Male genital opening coxal; female genital opening sternal. Male abdomen not elongate, not reaching level of anterior edge of base of chelipeds; telson not elongate, not twice length of segment 6. Male first gonopod long, slender, sinuous, hooked apically; second gonopod very short, sigmoid.

General References

Chia, D.G.B., Ng, P.K.L., & Castro, P. 1995. On a new genus and species of eumedonid crab from the Gulf of Carpentaria, northern Australia (Crustacea: Decapoda: Brachyura: Eumedonidae). Journal of Natural History 29: 1189-1195

Chia, D.G.B. & Ng, P.K.L. 1998. A revision of Ceratocarcinus White, 1847, and Harrovia Adams & White, 1849 (Crustacea: Decapoda: Brachyura: Eumedonidae), two genera of crabs symbiotic with crinoids. Raffles Bulletin of Zoology 46(2): 493-563

Ng, P.K.L. & Clark, P.F. 2000. The eumedonid file: a case study of systematic compatibility using larval and adult characters (Crustacea: Decapoda: Brachyura). Invertebrate Reproduction and Development 38(3): 225-252

Stevcic, Z. 1998. Evolutionary arrangement of the brachyuran families together with a checklist. Periodicum Biologorum 100(1): 101-104

Stevcic, Z., Castro, P. & Gore, R.H. 1988. Re-establishment of the family Eumedonidae Dana, 1853 (Crustacea: Brachyura). Journal of Natural History 22: 1301-1324

History of changes