Harpilius Dana, 1852

Bruce, A. J., 2004, A partial revision of the genus Periclimenes Costa, 1884 (Crustacea: Decapoda: Palaemonidae), Zootaxa 582, pp. 1-26 : 4-5

Genus Harpilius Dana, 1852

Harpilius Dana, 1852: 6 ; 17.

Diagnosis. Small to medium sized pontoniine shrimps of subcylindrical body shape. Carapace smooth, glabrous, with rostrum well developed, dorsally and ventrally dentate, without epigastric or supraorbital, spines, hepatic and antennal spines present, orbit obsolescent, inferior orbital angle distinct, without ventral flange. Abdomen smooth, glabrous, pleura rounded, posterolateral and posteroventral angles of sixth bluntly acute. Antennule with short stylocerite, statocyst with statolith; flagellum well developed, upper ramus with shorter flagellum multi­segmented. Antenna with basicerite with lateral tooth, scaphocerite well developed. Eye well developed, elongate, subcylindrical, cornea globular, ophthalmic somite without median process (= béc ocellaire). Mandible without palp; molar and incisor processes well developed. Maxillula with feebly bilobed palp. Maxilla normal, with simple palp, basal endite bilobed, coxal endite obsolete. First maxilliped with simple palp, basal and coxal endites feebly separate, broad, exopod with well developed flagellum, caridean lobe short, broad, epipod large, bilobed, distal lobe larger. Second maxilliped with normal endopod, dactylar segment narrow, exopod well developed, epipod small, subrectangular, without podobranch. Third maxilliped normal, ischiomerus distinct from basis, slender, exopod well developed, coxa with elongate lateral plate, generally with small or rudimentary arthrobranch. Thoracic sternites narrow, fourth with slen­ der finger­like median process, posterior sternites without acute processes. First pereiopods slender, chela with fingers simple. Second pereiopods well developed, robust, elongate, generally subequal, similar; major chela fingers without molar process and fossa, merus with distoventral tooth, carpus without distal teeth. Ambulatory pereiopods robust, propods without spines, dactyls simple, hamate, without basal process. Uropod with protopodite distolaterally dentate; exopod with small tooth and mobile spine distolaterally. Telson with two pairs of dorsal spines, three pairs of posterior spines.

Type species. By monotypy, Harpilius lutescens Dana, 1852 .

Etymology. “Name placed on the Official List of Generic Names in Zoology in Opinion 712, in 1964. Etymology (e): “the name of the genus is from, pruning hook, and alludes to the hooked form of the tarsus” (Dana, 1852, U.S. Explor. Exped., 13: 576); with tarsus the dactylus of the last three pereiopods is meant.” ( Holthuis, 1993). Gender: masculine.

Biology. Obligatory shallow water associates of scleractinian corals.

Systematic position. The genus Harpilius Dana. appears particularly closely related to two other pontoniine genera that are also obligatory scleractinian associates, Vir Holthuis, 1952 , and Philarius Holthuis, 1952 . Their general morphologies are very similar, and all have a well developed finger­like medial process on the fourth thoracic sternite. All species of these genera have simple hamate ambulatory dactyls. Vir is readily distinguished from Harpilius and Philarius by the presence of a palp on the mandibles. Philarius species are distinguished from both Vir and Harpilius species by the lack of an hepatic spine on the carapace. The mouthparts of H. lutescens have been illustrated by Dana (1855, partim), Kubo (1940a, as Periclimenes (Ancylocaris) amamiensis), Holthuis (1952, partim) and the sternal process and ambulatory dactyl of H. lutescens are illustrated by Bruce (1981a, fig. 1CD; 1992a, fig. 21B,D).