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Studies on Thalassinid Crustacea (Decapoda, Macrura Reptantia) with a Description of a New Jaxea from New Zealand and an Account of its Larval Development

2. The Family Laomediidae Borradaile, 1903

2. The Family Laomediidae Borradaile, 1903

The laomediids are rather rare, burrowing decapods, macrurous in form, regarded by some authors as true Anomura in their systematic relationships. The family is at present represented by three genera and six described species.

Laomedia de Haan is known from one species, L. astacina de Haan, 1849, from Japan and Korea (see de Man, 1928; Sakai, 1962). The authors know a large undescribed adult laomediid from eastern Australian shallow waters which also appears to belong to the genus Laomedia.

Jaxea Nardo is known from one named species, J. nocturna Nardo, 1847, from the Mediterranean and North Atlantic (see Selbie, 1914; Bouvier, 1940), and from four, apparently specifically distinct, but unnamed species known only by their larvae—in New Zealand waters (Gurney, 1924), off Samoa (Gurney, 1938), off New South Wales (Dakin and Colefax, 1940) and from the Adriatic Sea (Kurian, 1956). In Part II of this paper we wish to report the finding of the adults and all the larval stages of the New Zealand species which we propose to name Jaxea novaezealandiae n.sp.

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The remaining genus, Naushonia Kingsley, is known from four species: N. crangonoides Kingsley, 1897, from off Massachusetts (Atlantic Coast of U.S.A.); N. portoricensis (Rathbun, 1901) from Puerto Rico, West Indies; N. perrieri (Nobili, 1904) from the Red Sea, and N. macginitiei (Glassell, 1938) from Southern California (see Chace, 1939). Larval stages referred to Naushonia have been described from off New South Wales (Dakin and Colefax, 1940) and, with less certainty in generic placing, from off Samoa and from the Great Barrier Reef (Gurney, 1938).

The family Laomediidae, as now constituted, consists of those Thalassinidea having:— a linea thalassinica (a transverse, hinged groove along each side of the carapace) present; 1st pereiopods subequal, and chelate or subchelate; 2nd pereiopods subchelate or simple, never chelate; no appendix interna on pleopods; uropod with transverse suture on both endopod and exopod; podobranchs on at least 2nd and 3rd maxillipeds and 1st and 2nd pereiopods, and epipods on 1st to 4th pereiopods.

A Key to the Genera of the Laomediidae
1 (4) First pereiopods chelate, 5th pereiopods subchelate; antennal scale (scaphocerite) rudimentary or absent (Laomediinae)
2 (3) First pereiopods with stout and heavy chelae (hand length less than 2½ times hand width and less than carapace length), 2nd pereiopod subchelate or simple*; peduncles of both antennule and antenna short (penultimate segment of antennal peduncle subequal with ultimate) Laomedia de Haan, 1849
3 (2) First pereiopods with relatively heavy but elongated chelae (hand length three or more times hand width and subequal with or greater than carapace length); 2nd pereiopod subchelate; peduncles of both antennule and antenna elongated and relatively slender (penultimate segment of antennal peduncle at least four times ultimate) Jaxea Nardo, 1847
4 (1) First pereiopods subchelate, 2nd and 5th pereiopods simple; antennal scale well developed (Naushoniinae) Naushonia Kingsley, 1897