Corresponding author: Zdeněk Ďuriš (
Academic editor: S. De Grave
Based on recently published molecular phylogenies of Indo-West Pacific palaemonid shrimps and further morphological evidence, the systematic position of several species of the polyphyletic genus
Ďuriš Z, Horká I (2017) Towards a revision of the genus
The apparently polyphyletic and highly diverse palaemonid shrimp genus
Although several molecular studies were recently constructed (
Nevertheless, it is evident from the phylogeny in
Abbreviations: fcn, field collection number; , Muséum d’Histoire Naturelle, Geneve , Muséum National d’Histoire Naturelle, Paris , , Naturalis Biodiversity Centre (formerly Rijksmuseum van Natuurlijke Historie), Leiden
Holotype of
Feminine.
Subcylindrical body form. Carapace smooth; rostrum well developed, subequal to antennular peduncle and moderately high, dorsal margin convex, dentate, with first tooth postorbital, ventral margin convex, with 1–2 teeth on distal third of rostrum length. Inferior orbital angle produced, without reflected inner flange, supraorbital and epigastric teeth absent, antennal and hepatic teeth present. Fourth thoracic sternite with broad transverse ridge subdivided by deep narrow median incision. Pleon smooth, third tergite non-carinated or posteriorly produced, pleura 1–5 posteroventrally rounded; telson with 2 pairs of minute dorsal spines on distal third of telson length and 3 pairs of short posterior marginal spines. Ophthalmic somite without interocular process. Antennule and antenna as usual for the family; upper ramus of antennular flagellum biramous, with fused basal part; scaphocerite moderately broad, with small distolateral tooth falling short of anterior margin of lamina; carpocerite short. Eyes with small accessory pigment spot dorsally on corneal margin. Mandible without palp; molar and incisor processes normal. Maxilla with basal endite distinctly bilobed, coxal endite obsolete, scaphognathite normal; first maxilliped with endites fused, exopod well developed, with multiple terminal setae, caridean lobe normal, epipod feebly bilobed; second maxilliped with normal endopod, exopod as in first maxilliped, without caridean lobe, epipod small, simple, without podobranch; third maxilliped with slender endopod, ischiomerus fused or feebly separated from basis, exopod as in second maxilliped, coxa with semi-circular lateral plate, single arthrobranch present. First pereiopods slender, coxa with distomedial setose lobe, fingers of chelae elongate, with lateral cutting edges. Second pereiopods moderately stout, similar and subequal, chelae with fingers kept laterally; fingers subequal to palm, cutting edges with simple lamina and 2 low proximal teeth, carpo-propodal articulation simple, carpus much shorter than palm in adults, feebly cup-shaped. Ambulatory pereiopods slender, propodus without ventral spines, dactyli with minute or reduced distoventral tooth on stout corpus, unguis elongate, curved. Endopod of male first pleopod simple, elliptic, with multiple spinules medioproximally and multiple pappose setae distally. Male second pleopod with appendix masculina slender, with several simple terminal and lateral setae. Uropods normal.
While the species of the “
The sister taxon for
The earliest report on the present species was published by Zehntner in 1984. However,
Article 60.1 (
The single species in the genus is widely distributed throughout the whole Indo-West Pacific, from South Africa and Red Sea to Japan and Polynesia.
Carapace smooth; rostrum well developed, compressed, dorsal and ventral margins convex, with 7–10 dorsal teeth (posterior tooth behind orbits) and 0–2 ventral teeth, lateral carinae and orbit feebly developed, epigastric and supraorbital spines absent, inferior orbital angle usually produced, rounded, antennal tooth marginal, hepatic tooth close to level of latter. Pleon smooth, third segment not posteriorly produced, pleura rounded. Telson with two pairs of moderately large dorsal marginal spines situated on anterior and posterior thirds of telson length; three pairs of posterior spines, lateral spines smaller than dorsal spines. Eyes with globular cornea, small additional pigment spot dorsally on corneal margin. Antennule well developed. Antennal basicerite armed with lateral tooth; scaphocerite well developed, moderately broad, with distolateral tooth small, not reaching distal end of lamella. Mandible without palp, molar process robust, incisor process as usual for the family. Maxillula with bilobed palp, laciniae as usual for the family. Maxilla with simple palp, basal endite slender, deeply bilobed, coxal endite obsolete, scaphognathite moderately broad. First maxilliped with simple palp, basal endite fused with coxal endite, exopod with large caridean lobe, flagellum slender with several plumose distal setae, epipod feebly bilobed. Second maxilliped with normal endopod, propodus not produced distomesially, exopod similar to first maxilliped, without accessory lobe, coxa with oval epipod without podobranch. Third maxilliped with slender endopod, ischiomerus fused to basis, exopod as in second maxilliped, coxa with oval lateral plate, arthrobranch rudimentary or lacking. Fourth thoracic sternite with broad transverse ridge subdivided by median incision. First pereiopods moderately slender, chela with fingers subequal to palm, deeply subspatulate with entire cutting edges, coxa with setose distoventral lobe. Second pereiopods well developed, smooth, similar and equal, fingers with several small recurved teeth on proximal half, palm subcylindrical, longer than fingers, carpo-propodal articulation terminal, carpus much shorter than palm, merus unarmed, coxa without distoventral lobe. Ambulatory pereiopods moderately slender, propodus without ventral spines, dactyli with stout unarmed corpus, unguis elongate, curved. Endopod of male first pleopod simple, elliptic, feebly spinulose medioproximally, with several setulose setae distolaterally. Male second pleopod with appendix masculina slender, with several simple terminal and lateral setae. Uropods normal, exopod with small distolateral tooth and normal movable spine.
From
Based on recent molecular studies (
The three species of
Widely distributed in the Indo-West Pacific from the Red Sea and Kenya to Japan, Marshall Islands, and Fiji.
The species of the present genus are all obligate associates of sea anemones (
1 | Fourth thoracic sternite produced anteriorly, bilobed, lobes abutting but separated by narrow deep incision; colouration: body with dense longitudinal lines of orange dots, pereiopods dark purple/red spotted |
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– | Fourth thoracic sternite with U-shaped median incision; colouration: generally transparent except white band between eyes; adult females with white median band on bottom of thoracic and abdominal segments |
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2 | Ambulatory dactyli with unguis proximo-ventrally smooth (adult females with white median band on thoracic and abdominal segments) |
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– | Ambulatory dactyli with unguis proximo-ventrally serrated |
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Second pereiopod of species of the genus
Examples of species from the genera reported in this study.
Carapace smooth; rostrum well developed, subequal to antennular peduncle, compressed, usually with 5–7 low dorsal and 0–3 ventral teeth, lateral carinae with depressed supraorbital tooth, orbit feebly developed, epigastric tooth absent, inferior angle distinct, hepatic tooth close to antennal tooth and slightly lower positioned. Pleon smooth, fourth and fifth pleura posteroventrally angulate. Telson with two pairs of small dorsal spines on posterior half, and with three pairs of posterior spines. Eyes with globular cornea. Basal antennular segment with 2–3 acute distolateral teeth. Antenna with basicerite unarmed, scaphocerite moderately broad, with distolateral tooth small, not reaching distal level of lamina. Epistome with pair of lateral rounded tubercles. Mandible without palp, molar process robust, incisor process normal, with 3–4 terminal teeth; maxillula with bilobed palp, laciniae moderately broad; maxilla with simple palp, basal endite slender, feebly bilobed or simple, coxal endite obsolete, scaphognathite moderately broad; first maxilliped with simple palp, basal and coxal endites fused, exopod with distinct caridean lobe, flagellum slender with 4 plumose distal setae, epipod bilobed; second maxilliped with normal endopod, propodus feebly produced medially, exopod similar to flagellum of first maxilliped, coxa with elongate epipod without podobranch, arthrobranch rudimentary; third maxilliped with slender endopod, ischiomerus distinct from basis, exopod as in second maxilliped, coxa with large subcircular lateral plate, arthrobranch rudimentary. Fourth thoracic sternite without median process. First pereiopods slender, chela with fingers tapering distally and feebly or distinctly subspatulate with entire cutting edges, coxa with obsolete distoventral lobe. Second pereiopods similar and subequal; cutting edges of fingers dentate or denticulate; palm elongate, subequal or longer than fingers, subterminally articulated to short cup-shaped carpus, with pair of proximal lobes fitting dorsally to carpal cavity; carpus and merus unarmed. Ambulatory pereiopods slender, dactyli bi- or triunguiculate (i.e. with or without dorsal spinule behind unguis), unguis long, almost subequal to corpus length; propodus with ventral spinules and tufts of soft setae. Uropodal exopod elongate, laterally straight, with small distolateral tooth with mobile spine medially.
A combination of the subgeneric name
The present new genus is closely related to three crinoid-associated genera,
Widely distributed throughout the whole Indo-West Pacific region.
The genus
The genus
1 | Ambulatory dactyli triunguiculate; associated with crinoids (basal antennular segment with 2–3 acute teeth distolaterally; first pereiopod fingers simple, subequal to palm; second pereiopods with cutting edges of fingers dentate proximally and denticulate distally) |
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– | Ambulatory dactyli biunguiculate; associated with echinoids |
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2 | Palm and dactylus of first pereiopod strongly compressed, palm tuberculate dorsally, dactylus carinate medially; second pereiopods with cutting edges of fingers dentate throughout; basal antennular segment with 3 acute teeth distolaterally |
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– | Palm and dactylus of first pereiopod normal, smooth dorsally, uncarinate; second pereiopods with cutting edges of fingers dentate proximally and denticulate distally; basal antennular segment with rounded lobe and 2 acute teeth distolaterally |
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In addition to the type series (
Medium sized shrimps. Carapace smooth, with antennal and hepatic teeth; epigastric tooth lacking or, if present, clearly separated from them; hepatic tooth subequal and situated posteriorly of antennal tooth and slightly below. Rostrum slender, dorsal lamina bearing 6–10 teeth, ventral lamina obsolete, with 1–2 subterminal teeth. Inferior orbital angle produced, rounded. Pleon smooth, pleura posteroventrally rounded; telson slender, tapering distally, with 1–2 pairs of small dorsal spines and three pairs of posterior marginal spines. Ophthalmic somite without interocular process. Antennula and antenna normal, scaphocerite 3–4 times longer than broad. Eye with globular cornea and small accessory pigment spot, stalk distinctly longer than corneal diameter. Mandible without palp, incisor and molar processes stout. Maxillula with bilobed palp, upper and lower laciniae well developed. Maxilla with slender palp, well developed scaphognathite, distal (basal) endite bilobed; proximal (coxal) endite lacking. First maxilliped with simple palp, basal endite broad, coxal endite feebly demarcated, exopod well developed, caridean lobe normal, epipod distally bilobed. Second maxilliped with normal endopod and exopod, epipod small, simple, without podobranch. Third maxilliped with slender segments, ischiomerus and basis fused; exopod well developed, coxa with rounded lateral plate, single small arthrobranch present. Fourth thoracic sternites without special structures. First pereiopods slender, fingers narrow, simple, with dense tufts of long setae on sides, coxa with or without distoventral setose process, basis unarmed. Second pereiopods long and slender, distinctly unequal in length; major pereiopod overreaching scaphocerite by distal part of merus in adults; fingers simple, cutting edges entire or with 1–2 feebly developed teeth on proximal third of minor chela, and with 2–4 obtuse proximal teeth on major chela fingers; major pereiopod with palm 2.5–5 times longer than fingers. Ambulatory pereiopods slender, propodus with prehensile structure of long straight distoventral spines arranged to 2–5 pairs, spines longer than distal propodal depth; dactyli slender and curved, simple, or with distinct or minute distoventral tooth. Endopod of first male pleopod with angulate apex and distinct medial lobe; second male pleopod with appendix masculina with 3 terminal serrated setae and 2 lateral setae. Uropods normal; distolateral angle of exopod with small tooth and movable spine medially.
Combination of
Based on the recent molecular phylogeny in
Madagascar; Maldive Islands; Indonesia; Vietnam and Taiwan, South China Sea; Japan; Heron Island, Great Barrier Reef, Australia.
The species of the present genus have been recorded as associated with antipatharians, hydroids, pennatularians, and scyphozoans (
The generic name
(modified from
1 | Major second pereiopod extremely long and slender, overreaching scaphocerite by proximal merus, carpus longer than both chela or merus; walking dactyli feebly biunguiculate with small distoventral tooth on corpus, propodi with long spines arranged to 4 distoventral pairs |
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– | Second pereiopods unequal, slender, at least overreaching scaphocerite by distal merus, carpus subequal or distinctly shorter than both chela or merus; walking dactyli simple or with rudimentary distoventral tooth, propodi with 1–3 single proximal spines in addition to 2–4 distoventral pairs of long spines |
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2 | Major second pereiopod with palm granulate; minor second chela with 1–2 teeth on cutting edges |
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– | Major second pereiopod with palm smooth; minor second chela with cutting edges entir |
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Additional specimens were kindly provided for examination by Ryo Minemizu (Shimizu, Japan), and Chia-Wei Lin (
Illustrative photos were obtained, or figures were prepared from specimens collected during the authors’ trips to Vietnam, and during: (1)
Sammy De Grave (