Pinnotherotonia rumphiusi, Marin, Ivan & Paulay, Gustav, 2010

Marin, Ivan & Paulay, Gustav, 2010, Pinnotherotonia rumphiusi gen. et sp. nov., a new furry bivalve-associated pontoniine shrimp (Crustacea: Decapoda: Palaemonidae) from Palau, Zootaxa 2636, pp. 37-48 : 38-46

publication ID	https://doi.org/ 10.5281/zenodo.198455
DOI	https://doi.org/10.5281/zenodo.6205799
persistent identifier	https://treatment.plazi.org/id/039A5E02-FF92-FF9C-A2B1-F992515CFA0A
treatment provided by	Plazi
scientific name	Pinnotherotonia rumphiusi
status	sp. nov.

Treatment

Pinnotherotonia rumphiusi View in CoL sp. nov.

( Figs. 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Material examined. Holotype, ovigerous female, pcl 6.2 mm (UF 3032), Pacific Ocean, Palau, Koror Island, Iwayama Bay, in mantle cavity of Periglypta crispata , 0–10 meters, coll. G. Paulay, 0 1 July 1999. Diagnosis. As for the genus.

Description. Medium-sized furry pontoniine shrimp with swollen, slightly depressed body ( Fig. 1 View FIGURE 1 ). Carapace ( Fig. 2 View FIGURE 2 A, B) swollen, oval, densely covered with small setae, without teeth, with pterygostomial angle bluntly produced. Rostrum ( Figs. 2 View FIGURE 2 C–E, 3A) robust, broad, not tapering, reaching to distal margin of antennular peduncle, curved downward, dorsally and ventrally unarmed, ventral carina forming distinct keel between antennular segments ( Fig. 2 View FIGURE 2 E), with slightly developed lateral carina ( Fig. 3 View FIGURE 3 A).

Abdominal somites densely covered with setae, unarmed; tergites non-carinate, not posteriorly produced; pleurae of first to third pleomeres posteroventrally rounded; three last pleomeres small, with feebly developed pleurae (fig. 1B); distal and distoventral margins of sixth pleomere rounded ( Fig. 3 View FIGURE 3 B). Telson ( Fig. 3 View FIGURE 3 B, C) stout, densely covered with small setae, about 1.2 times as long as wide proximally, tapering distally, with two pairs of small, stout dorsal spines, each about 0.08 of telson length, inserted at about 0.3 and 0.7 telson length, respectively ( Fig. 3 View FIGURE 3 C); posterior margin tapering, bluntly rounded (fig. 3C), without spines, with a row of long, submarginal setae ( Fig. 3 View FIGURE 3 D).

Eyes ( Fig. 2 View FIGURE 2 F) large, swollen, thick, dorsally covered with simple setae; cornea rounded, slightly reduced, pigmented; eyestalk stout, swollen, cylindrical, about as long as wide.

Antennule and antenna reduced, mostly covered by eyes and carapace ( Fig. 2 View FIGURE 2 C, E). Antennule ( Fig. 3 View FIGURE 3 G) stout, basal peduncular segment robust, about as long as its proximal width, with straight lateral margins, without ventromesial or distolateral tooth ( Fig. 3 View FIGURE 3 H); stylocerite stout, bluntly rounded distally, almost reaching to the distal margin of basal segment; second and third segments stout, unarmed, about 0.5 times as long as wide; lateral flagellum thick, main ramus with 4 segments, accessory ramus with 2 segment; mesial flagellum filiform, with 6 segments. Antenna ( Fig. 2 View FIGURE 2 B) stout; basicerite stout, about twice wider than long, with distolateral margin unarmed; carpocerite robust, slightly overreaching scaphocerite, about twice as long as wide; scaphocerite reduced, ear-shaped, without distolateral tooth, blade rounded distally.

Epistome with blunt medial carina; labrum suboval ( Fig. 2 View FIGURE 2 E). Mandible ( Fig. 4 View FIGURE 4 A–C) well developed, without palp; molar process well-developed, stout; incisor process slender, tapering distally, with four large triangular teeth distally ( Fig. 4 View FIGURE 4 C). Maxillule ( Fig. 4 View FIGURE 4 D) with well-developed, bilobed palp, dorsal lobe blunt, ventral lobe with small and curved spine ( Fig. 4 View FIGURE 4 E); dorsal lacinia broad, expanded distally, distal margin bluntly rounded and covered with a row of small stout spines and numerous simple setae; ventral lacinia slender, not reaching to the distal margin of dorsal lacinia, with simple long setae distoventrally and marginally. Maxilla ( Fig. 4 View FIGURE 4 F) normal, with tapering, simple palp; endites stout; basal endite simple, distally bluntly rounded, furnished with stiff, elongated setae; coxal endite well-developed, distally bluntly rounded, furnished with long simple setae; scaphognathite broad, furnished with short plumose setae. First maxilliped ( Fig. 4 View FIGURE 4 G) normal; epipod triangular, with medial notch; exopod slender, with expanded caridean lobe; basal and coxal endites completely fused, excavated, furnished with long simple setae distally; palp slender, rounded distally, without distal setae. Second maxilliped ( Fig. 4 View FIGURE 4 H) with robust segments; epipod normal, earshaped; exopod slender reaching to propodal segment, with long simple setae distally; distolateral margin of propodus broadly rounded, dorsal margin convex, furnished with slender setae; dactylus about 3 times as long as broad, with numerous medium stout spines and numerous simple setae along distal margin. Third maxilliped ( Fig. 4 View FIGURE 4 I) stout; epipod rounded, arthrobranch absent; exopod slender, overreaching antepenultimate segment; antepenultimate segment stout, about 3 times as long as wide, with basis and ischiomerus separated by oblique, well-marked suture; penultimate segment about three times as long as wide, with convex bluntly produced mesioventral margin; ultimate segment slender, equal to penultimate segment, about three times as long as wide, tapering distally, with tufts of long setae along ventrolateral margin, with several long setae distally.

First pereiopod ( Fig. 4 View FIGURE 4 A) relatively slender, densely covered with small setae, segments unarmed; coxa, with well marked, rounded distoventral lobe; basis about 1.5 times as long as wide; ischium about twice as long as wide; merus slender, about 4 times as long as wide, with straight ventral and convex dorsal margins; carpus long and slender, widening distally, slightly longer than merus, about twice longer than chela, about 4.5 times as long as maximal width; palm about twice as long as wide, subcylindrical in cross-section; fingers ( Fig. 5 View FIGURE 5 C) slender, subcylindrical, about 4 times as long as proximal width, with simple tips and straight cutting edges.

Second pereiopods equal in size and shape ( Fig. 1 View FIGURE 1 A), with unarmed segments, densely covered with small setae ( Fig. 5 View FIGURE 5 D); basis rectangular; ischium widening distally, about 1.5 times as long as maximum width; merus stout, about 1.2 times as long as maximum width, with concave ventral and convex dorsal margins; carpus stout, swollen, widening in medial part, about 1.2 times as long as maximum width; palm subcylindrical in cross-section, tapering distally, about twice as long as maximum width; fingers robust, about half of the length of palm, about 2.3 times as long as wide, with several small teeth in proximal half and straight cutting edges distally, with acute, curved tips.

Third pereiopod ( Fig. 5 View FIGURE 5 G) stout, densely covered with small setae; basis rectangular, about as long as wide; ischium about 1.7 times as long as wide; merus about 2.3 times as long as wide, with straight ventral and convex dorsal margins; carpus stout, widening distally, about 1.5 times as long as merus, about half of the length of propodus, with bluntly projected distodorsal margin slightly overlapping carpo-propodal articulation, with straight ventral and convex dorsal margins; propodus about 3.2 times as long as wide, slightly tapering distally, ventrally unarmed, without distoventral teeth, with straight ventral and convex dorsal margins; dactylus ( Fig. 6 View FIGURE 6 A) with broken unguis, stout, about 1.6 times as long as wide, with medial and proximal parts covered with small simple setae, with numerous long and simple, proximally-curved setae on distal and disto-ventral margins. Fourth and fifth pereiopods similar to third; dactylus of fourth pereiopod ( Fig. 6 View FIGURE 6 B), stout, biunguiculate, with medial and proximal parts covered with small, simple setae, with numerous long and simple, proximally curved setae on distal and distoventral margins; main unguis ( Fig. 6 View FIGURE 6 C) long and slender, smooth, with oblique tip bearing several small teeth, sharp distally; accessory unguis small, simple, triangular, with sharp and curved tip.

Pleopods densely covered with small setae, without specific differentiating features. Uropods stout, densely covered with small setae ( Fig. 3 View FIGURE 3 B) not exceeding telson; lateral margin of uropodal exopod slightly convex ( Fig. 3 View FIGURE 3 E), with bluntly rounded distolateral angle, with stout curved distolateral spine ( Fig. 3 View FIGURE 3 F); dieresis simple.

Colouration. General appearance semi-transparent with orange-red mass of gonads and eggs in carapace and under abdomen respectively; the body and appendages covered with small, diffuse white dots ( Fig. 7 View FIGURE 7 ).

Etymology. The species is named after Georg Eberhard Rumphius (1627–1702), a German-born botanist employed by the Dutch East India Company, who published the first detailed observations on the natural history of the Moluccas, Indonesia, still referred to today. During the study of the fauna of Indonesia, Rumphius (1705) mentioned small, semi-translucent shrimps covered with small white dots and with slender, white legs living inside the lettered venus clam Tapes literatus (Linnaeus 1758) (Veneridae) at Amboina. These shrimps have never been identified, nor recorded again since. Fransen (2002) suggested that they could represent Bruceonia ardeae , a species with the same coloration. However, B. ardeae is known only from the epifaunal Chama pacifica Broperip, 1835 (Chamidae) , not from infaunal, burrowing venerids. It is more probable, that Rumphius’ shrimps represent Pinnotherotonia rumphiusi or a yet unidentified congener.

Host. The species is known only from one specimen of Periglypta crispata (Deshayes 1853) (Veneridae) . Periglypta crispata is the second most wide-ranging species of its genus, extending from the Red Sea and East Africa to the Line and Tuamotu Islands. It lives shallowly buried in coarse sands at least between 5-30 m depths. It is most common in lagoons, although also occurs on sheltered (or deep) outer reef slopes. It grows to a maximum length of 95 mm, although its close relative (and possible ecomorph) Periglypta clathrata (Deshayes 1853) reaches ~ 115 mm in length (Paulay, unpublished). These species are not frequently encountered alive, which may in part explain the lack of previous and other records on P. rumphiusi . Overall Periglypta comprises 10 currently-recognized species, 8 in the Indo-west Pacific and one each in the East Pacific and West Atlantic (Paulay, unpublished). GP has collected and opened dozens of specimens of Periglypta from across the Indo-west Pacific and only found commensal shrimp in this one specimen.

Distribution. Only known from the type locality, Palau.