Manipontonia, Bruce, A. J., Okuno, J. & Li, Xinzheng, 2005

Bruce, A. J., Okuno, J. & Li, Xinzheng, 2005, Manipontonia gen. nov., a new pontoniine shrimp genus for Periclimenes psamathe (De Man) (Crustacea: Decapoda: Palaemonidae), Zootaxa 926, pp. 1-11 : 3-6

Manipontonia gen. nov.

Figs 1–3

Diagnosis: Medium sized pontoniine shrimps of slender subcylindrical body form. Carapace smooth; rostrum well developed, long, slender, oval in section, dorsal margin dentate, two proximal teeth large, ventrally denticulate, distal teeth small, simple, ventral margin non­dentate, epigastric tooth large, as proximal rostral teeth, inferior orbital angle produced, without reflected inner flange, supraorbital spines absent, antennal and hepatic spines present. Abdomen smooth, third tergite non­carinate or posteriorly produced, posterior margin entire; pleura posteroventrally rounded; telson with two pairs of dorsal spines and three pairs of posterior marginal spines. Ophthalmic somite without béc ocellaire. Antennule and antenna normal, upper ramus of antennular flagellum biramous, shorter ramus well developed, scaphocerite well developed. Eyes with well pigmented globular cornea. Epistome unarmed. Paragnath ( Fig. 2 A) bilobed, rounded. Mandible without palp; molar and incisor processes normal. Maxillula with bilobed palp, upper and lower laciniae broad; maxilla with slender palp, basal endite bilobed, coxal endite obsolete, scaphognathite normal; first maxilliped with simple palp, basal endite broad, coxal endite smaller, exopod well developed with terminal plumose 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 ( Fig. 2 ) with slender endopod, ischiomerus and basis completely fused, exopod as second maxilliped, coxa without ventromedial process, with rounded lateral plate and single small arthrobranch, without pleurobranch Fourth thoracic sternite without finger­like median process, fifth to eighth unarmed. Fourth to eighth thoracic segments with pleurobranchs. First pereiopods slender, with fingers of chelae simple. Second pereiopods very slender, markedly unequal in length, dissimilar in shape, major second pereiopod highly elongate, chela and carpus finely tuberculate, fingers simple, cutting edges dentate, without molar process and fossa; minor second pereiopod small, chela and carpus smooth, fingers unarmed; ambulatory pereiopods slender, dactyls simple. Pleopods normal; male first pleopod endopod with well developed appendix interna bearing terminal cincinnuli. Uropods normal.

Type species: By monotypy: Urocaris psamathe De Man, 1902: 816 –822, pl. 25 fig. 51, 51a–i. Holotype, ovigerous female, Senckenberg Museum, SMF 8530. The specimen is in good condition (A. Allspach, pers. comm., 20­5­03). The genus is presently monospecific.

Systematic position: Shrimps of the genus Periclimenes are considered to be diverse, including over 150 species. However, Periclimenes seems to be polyphyletic, and indeed, recent taxonomic studies showed that several species previously recognized as Periclimenes should be removed to other genera (see Bruce, 1975b; Duris & Bruce 1995; Bruce 1994; Bruce 2004). The problem remains that many species of Periclimenes should be reviewed for their taxonomic status to be more accurately determined. The result of the present paper is a further small step in this direction.

Manipontonia is readily separated not only from Periclimenes but also from all other genera of the subfamily Pontoniinae characterised by antennal and hepatic spines and exopods on all maxillipeds, and by the combination of the following features: the long and slender rostrum with ventral margin unarmed, the proximal rostral dorsal teeth and the epigastric tooth with fine ventral denticulations, and the endopod of the male first pleopod with a developed appendix interna terminally with only a few cincinnuli.

As pointed out by Bruce (1978), Manipontonia is similar to Urocaridella , in the subfamily Palaemoninae , in having the long, slender and dorsally sinuous rostrum, and the proximal rostral dorsal teeth and epigastric spine ventrally with fine denticulation. From Urocaridella , Manipontonia is distinguished by several morphological features: 1) the rostral ventral margin unarmed (vs. armed with several teeth in Urocaridella ); 2) the fourth thoracic sternite without median process (vs. acute median process present in Urocaridella ); 3) the epipod of second maxilliped without podobranch (vs. developed podobranch present on epipod in Urocaridella ); 4) the third maxilliped with single arthrobranch (vs. two arthrobranchs in Urocaridella ); 5) the second pereiopods extremely unequal in length, with carpus and palm of the major second pereiopod finely tuberculate (in Urocaridella , the second pereiopods are similar in shape and subequal in length, with carpi and palm smooth).

Etymology: Named in honour of Johannes Govertus de Man (1850–1930), who provided the beautifully illustrated original description of Urocaris psamathe ( De Man, 1902) , combined with Pontonia Latreille, 1829 . Gender, masculine.

Hosts: Associated with gorgonians, antipatharians, alcyonarians and hydroids.

Figures

FIGURE 1. Manipontonia psamathe (De Man) comb. nov., male, Heron Island Queensland, QM W 26808. Scale bar in millimetres.

FIGURE 2. Manipontonia psamathe (De Man) comb. nov. A, paragnath. B, third maxilliped, basal and coxal region, medial aspect. D, male first pleopod, endopod. D, same, median lobe. E, male second pleopod, appendices. A, Maldive specimen; B, Heron Island specimen; CDE, Singapore specimen.

FIGURE 3. Manipontonia psamathe (De Man) comb. nov., female, CMNH­ZC 0 1402, Boso Peninsula, Kamogawa, Honshu, Japan (photograph J. Okuno).