Palaemonella meteorae, Bruce, 2008

Bruce, A. J., 2008, A new species of Palaemonella Dana, 1852, (Crustacea: Decapoda; Pontoniinae) from the Red Sea, Zootaxa 1844 (1), pp. 63-68 : 64-67

publication ID	https://doi.org/ 10.11646/zootaxa.1844.1.6
persistent identifier	https://treatment.plazi.org/id/03D86179-7164-FFC9-FF1D-8CD1FD55FE78
treatment provided by	Felipe
scientific name	Palaemonella meteorae
status	sp. nov.

Treatment

Palaemonella meteorae View in CoL sp. nov.

( Figs 1–2 View FIGURE 1 View FIGURE 2 )

Material examined. 1 ♂ holotype, Red Sea, off Port Sudan, RV Meteor, stn. Me5-154 Ku, 19°33.3'N 37°16.4'E – 19°33.9'N 37°16.2'E, 519–544m depth, beam trawl, 20 February 1987, SMF 32615 GoogleMaps . 1 ♀ allotype (dissected), idem, SMF 32616 GoogleMaps .

Diagnosis. A small Palaemonella with rostrum reaching to about middle of distal segment of antennular ped-uncle, dentition 6/2, all dorsal teeth pre-orbital, ventral margin densely setose, without supraorbital spines or tubercles, supraorbital or post-orbital ridges, epigastric spine at 0.36 of CL, antennal spine well developed, exceeding inferior orbital angle, hepatic spine in branchiostegal position, distolateral tooth of scaphocerite scarcely exceeding lamella, labrum with anterior median carina with ventral beak, with adjacent long rigid submedian seta, mandible with small single segmented palp, fourth pleuron posteroventrally rounded, fifth acute,

Description. Generally closely similar to P. komaii ( Fig. 1A View FIGURE 1 ). Rostrum ( Fig. 1D View FIGURE 1 ) about 0.88 of CL, slen- der, reaching to about middle of distal segment of antennular peduncle, with 6 slender acute teeth dorsally, all anterior to the posterior orbital margin, each with 2–3 short interdental setae, 2 smaller acute teeth distoventrally, ventral margin with numerous long plumose setae, epigastric spine at 0.36 of CL, orbit ( Fig. 1 View FIGURE 1 BC) obsolescent, without postorbital or supraorbital ridges, spines or tubercles, inferior orbital angle slightly produces, rounded, antennal spine well developed, marginal, exceeding inferior orbital angle, hepatic spine in branchiostegal position, similar to antennal spine. Posterior margin of third abdominal tergite with palisade of minute denticles. Sixth segment 0.38 of CL, posteroventral and posterolateral angles acute, first to fourth pleura rounded, fifth with small posteroventral tooth. Antennal basicerite with small distolateral tooth, scaphocerite ( Fig. 1E View FIGURE 1 ) 4.0 times longer than central width, distolateral tooth ( Fig. 2A View FIGURE 2 ) short, stout, scarcely exceeding lamella. Ophthalmic somite with small rounded median process. Epistome with small anterolateral boss. Cornea ( Fig. 1F View FIGURE 1 ) well developed, deeply pigmented, diameter 0.22 of CL, accessory pigment spot obscure. Labrum ( Fig. 1G View FIGURE 1 ) near vertically orientated, 1.25 times broader than long, with median carina with small acute ventral beak with adjacent posteroventrally directed submedian setae ( Fig. 2B View FIGURE 2 ), about 0.2mm long. 0.05mm wide at base. Mandible ( Fig. 1H View FIGURE 1 ) normal, palp ( Fig. 2C View FIGURE 2 ) with single small segment, about one sixth of incisor process length, 2.2 times longer than central width, distolaterally, with three short simple setae, incisor process with three acute teeth on each side, molar process with four stout marginal teeth distally. Third maxilliped epipod rounded, not posteriorly angular, without arthrobranch. Fourth thoracic sternite ( Fig. 1I View FIGURE 1 ) with median process robust. First pereiopod coxa ( Fig. 2D View FIGURE 2 ) with robust bilobed ventral process, with stout short spines. Male first pleopod normal. Endopod ( Fig. 2E View FIGURE 2 ) distally expanded, without medial accessory lobe, rounded, about 3.2 times longer than maximal width, with about 12 short slender simple setae distally. Second pleopod ( Fig. 2F View FIGURE 2 ) normal, with appendices ( Fig. 2G View FIGURE 2 ) at about 0.3 of length, appendix masculina slightly exceeding appendix interna, subcylindrical, 6.0 times longer than width, with about 10 slender simple marginal setae terminally and distolaterally; appendix interna similar, with few distal cincinnuli only. Caudal fan as in P.komaii . Telson ( Fig. 1J View FIGURE 1 ) about 0.35 of CL, with dorsal spines at about 0.4 and 0.7 of telson length, dorsal spines larger than lateral posterior spines, posterior margin truncate with subquadrate median process ( Fig. 1K View FIGURE 1 ) bearing sparsely setulose submedian spines, about 0.45 of intermediate spine length, intermediate spines about 0.25 of telson length, 6.7 times lateral spine length.

Systematic position. Palaemonella meteorae closely resembles P. komaii Li & Bruce, 2006 . These species can be distinguished from all other Indo-West Pacific species of Palaemonella by the position of the hepatic spine which is placed anteriorly, slightly behind the anterior carapace margin and lower level than in other species, near the ventral margin, in a branchiostegal position. Palaemonella meteorae can be distinguished from P.komaii by the absence of a post-orbital carina, of post-orbital rostral teeth, an epigastric spine at 0.25 of CL, vs 0.29. the distolateral spine of the scaphocerite robust, only slightly exceeding the lamella, vs slender, distinctly exceeding lamella and shorter stouter mandibular palp.

Measurements (mms). Holotype male, postorbital carapace length, 2.9; carapace and rostrum, 4.4; total body length (approx.), 11.3. Female allotype, postorbital carapace length, 2.8.

Etymology. The species is named after the IFM-GEOMAR research ship Meteor, which has carried out extensive research in the Red Sea.

Remarks. Apart from the lack of pereiopods, the holotype is in good condition. The female allotype, now dissected, lacks the rostrum and posterior telson as well as all pereiopods.

Palaemonella dolichodactylus , P. hachijo Okuno. 1999 and P.komaii are included in the “ P. dolichodactylus species complex” proposed by Li & Bruce (2006). Some other taxa should also be included. The shrimp initially reported by Bruce (1979, 1982) from Hong Kong as Periclimenes ? digitalis has been previously referred to Palaemonella ( Bruce, 2003) and noted as closely related to P. dolichodactylus . Together with P. hachijo and P.komaii ( Bruce, 2003) , also included is Palaemonella sp. ( Li et al. 2008). Like P. meteorae , it is another unfortunately damaged and incomplete specimen. The group now comprises six taxa ranging from shallow waters to over 500m depths.

The labrum has rarely been detailed in taxonomic descriptions of the Palaemonidae . Borradaile provides a brief mention of the labrum in Palaemon serratus (as Leander ) ( Borradaile, 1917: 71, figs 44, 45, 51). In Palaemonella rotumana ( Borradaile, 1898) the labrum is generally similar to P. meteorae but the median carina appears longer and less beaked ventrally, with a transverse row of slender setae extending laterally to the beak, the submedian setae the shortest, the next lateral the longest, with the lateral three decreasing in length laterally (ovig. ♀, CL 2.5mm, Leven Reef, Mombasa, Kenya, QM W28439). The longest seta has a length of only 0.15mm. It may be noted also that in this specimen the inferior orbital angle in dorsal view is very small and highly acute in comparison with P. meteorae .