Family HYMENOSOMATIDAE MacLeay, 1838

Elamena abrolhensis [from Hale 1927: fig. 117]

Halicarcinus rostratus [from Hale 1927: fig. 114]

Trigonoplax longirostris [from Hale 1927: fig. 118]

Museums

Regional Maps

• Hymenosomatidae MacLeay, W.S. 1838. On the Brachyurous Decapod Crustacea brought from the Cape by Dr Smith. pp. 53–71 pl. 3 in, Illustrations of the Annulosa of South Africa; being a portion of the objects of natural history collected during an expedition into the interior of South Africa, under the direction of Dr Andrew Smith, in the years 1834, 1835, and 1836; fitted out by "The Cape of Good Hope Association for Exploring Central Africa". London. 75 pp. 4 pls [68] [as Hymenosomidae; Holthuis, L.B. 1968. On Hymenosomatidae (Crustacea Decapoda Brachyura) from fresh water, with the description of a new species. Beaufortia 15(195): 109–121 figs 1–3 discussed and clarified the nomenclatural status of the name].

  Secondary source:

   Holthuis, L.B. 1968. On Hymenosomatidae (Crustacea Decapoda Brachyura) from fresh water, with the description of a new species. Beaufortia 15(195): 109-121 figs 1-3.
• Hymenicinae Dana, J.D. 1851. On the classification of the Crustacea Grapsoidea. American Journal of Science and Arts 12: 283-290 [290].

Taxonomic Decision for Synonymy

• Manning, R.B. & Holthuis, L.B. 1981. West African Brachyuran Crabs (Crustacea: Decapoda). Smithsonian Contributions to Zoology No. 306: i-xii, 1-379 figs 1-88, 2 appendices [251]

Introduction

Hymenosomatids, like Majidae, are often referred to as `spider crabs', although `false spider crabs' is more appropriate. They are small (carapace width 2–26 mm) and inconspicuous, and apparently often have been overlooked by collectors. For this reason, distribution patterns are still poorly understood. The smallest mature female brachyuran to be reported is a hymenosomatid, Elamenopsis minima Lucas & Davie, a mere 1.7 mm carapace width.

The majority of hymenosomatids occur in shallow marine coastal waters, on coral reefs, and have been found penetrating up estuaries into brackish and fresh waters. Although a few species burrow into sandy and muddy substrates, they do not construct permanent burrows. Most species live associated with sessile encrusting organisms, under dead wood, and in crevices and holes in rocks and in living or dead coral. Lucas (1980) gave an extensive review of biological data, including life cycles, growth, reproduction, reproductive strategies, behaviour, ecology and zoogeography. The phylogenetic position of the family has been a matter of conjecture for many years. Guinot & Richer de Forges (1997) argued that it is closely allied to the American majid subfamily Inachoidinae Dana (they treated it as a family in the superfamily Majoidea), but Guinot (2011) has most recently alternatively argued that hymenosomatids are more closely related to thoracotremes because the male gonopore is in fact sternal. In Australia, nine genera and 31 species are currently recognised. The most recent Australian revisionary studies are those of Lucas (1980) and Lucas & Davie (1982). Guinot (2011) has recently recognised two subfamilies.

Diagnosis

Cephalothorax dorso-ventrally thin, cuticle not heavily calcified, without hooked setae; dorsal carapace surface flat or nearly flat, often with strong gastro-cardiac groove and contiguous grooves; without orbits or with very incomplete orbits, eyes exposed and little retractile; antennular fossae shallow and poorly defined; antennae fused with epistome (when present), second segment slender; ischium of third maxillipeds well developed, palp articulating near anterolateral angle of merus; chelipeds not longer than twice carapace width in females and most males, fingers not bent at an angle to palm; male and female abdomens with not more than five segments, excluding telson; male genital apertures sternal; female genital apertures on sternites of first walking legs. (After Lucas 1980).

General References

Guinot, D. 2011. Odiomarinae nov. subfam., a new subfamily for two primitive genera of Hymensomatidae MacLeay, 1838, with preliminary remarks on the family (Crustacea, Decapoda, Brachyura). Zootaxa 2732: 20-32

Guinot, D. 2011. The position of the Hymenosomatidae MacLeay, 1838, within the Brachyura. Zootaxa 2890: 40–52

Guinot, D. & Richer de Forges, B. 1997. Affinités entre les Hymenosomatidae MacLeay, 1838 et les Inachoididae Dana, 1851 (Cructacea, Decapoda, Brachyura). Zoosystematica Rossica 19(2–3): 453-502

Lucas, J.S. 1980. Spider Crabs of the family Hymenosomatidae (Crustacea: Brachyura) with particular reference to Australian species: Systematics and biology. Records of the Australian Museum 33(4): 148-247 figs 1-10

Lucas, J.S. & Davie, P.J.F. 1982. Hymenosomatid crabs of Queensland estuaries and tidal mud flats, including descriptions of four new species of Elamenopsis A. Milne Edwards and a new species of Amarinus Lucas. Memoirs of the Queensland Museum 20(3): 401-419

History of changes