Nippontonia ashmoriensis, Bruce, A. J., 2014

Bruce, A. J., 2014, Nippontonia ashmoreiensis sp. nov., (Crustacea: Decapoda; Pontoniinae) from Ashmore Reef, Western Australia, Zootaxa 3847 (3), pp. 437-445 : 437-444

publication ID	https://doi.org/ 10.11646/zootaxa.3847.3.8
publication LSID	lsid:zoobank.org:pub:93B69DBC-9A53-47A4-A830-F65B9E145DE6
DOI	https://doi.org/10.5281/zenodo.6132920
persistent identifier	https://treatment.plazi.org/id/1C66BD4E-FFC1-FFFA-C5FE-F9BBFE6674A2
treatment provided by	Plazi
scientific name	Nippontonia ashmoriensis
status	sp. nov.

Treatment

Nippontonia ashmoriensis sp. nov.

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

Material examined. 1 ♂, holotype, Ashmore Reef, Western Australia, north side, lagoon middle entrance, 12° 11' 40.128"S 123° 3 ' 0.54"E, 7 m, 1 October 2013, coll. M. Ekins, WAM C54941. 3 ♀ (1 ovig.), paratypes, idem, WAM W54940 View Materials .

Description. Medium-sized shrimp, male with slender subcylindrical anterior body shape, females with body swollen.

Holotype male with carapace ( Fig. 1 View FIGURE 1 A) smooth, lacking one first pereiopod, minor second pereiopod and with one detached ambulatory pereiopod only.

Rostrum ( Fig. 4 View FIGURE 4 A) obsolescent, compressed, acute, with small acute dorsal tooth, intervening space to tip with five minute denticles, three simple setae, lateral carina undeveloped. Carapace ( Fig. 1 View FIGURE 1 A) about twice as long as deep in lateral view, compressed, with small antennal angle; supraorbital, epigastric, and hepatic teeth absent, anterolateral angle anteriorly produced, rounded.

Abdomen slender, pleura reduced, sixth segment with posterolateral angle rounded, posteroventral angle larger, acute; caudal fan as in paratype female 2.

Anterior appendages to carapace as in paratype female 2. Mouthparts not examined.

First pereiopod ( Fig. 1 View FIGURE 1 B) small, short, generally as in paratype female 2, chela about 0.35 of CL, palm smooth, fingers about 0.4 of palm length, carpus 0.77 of palm length, slightly swollen subdistally, 2.3 times longer than central depth, merus subcylindrical, slightly bowed, 1.2 times chela length,1.4 times carpus length, ischium subequal to carpal length, 2.8 times longer than distal width, basis and coxa without special features, coxa without medial process.

Major second pereiopod ( Fig. 1 View FIGURE 1 C) well developed, robust, slender, chela about 1.33 of CL, palm smooth, glabrous, 0.82 of CL, oval in section, posterodorsally protuberant, 2.8 times longer than proximal depth, tapering distally to 0.5 of proximal depth, fingers ( Fig. 1 View FIGURE 1 D) about 0.35 of palm length, incurved; dactyl medially subspatulate, 4.0 times longer than proximal depth, cutting edge laminar, entire, with rounded process proximally, inner margin with similar smaller process more proximally, with stout feebly hooked tip; fixed finger 3.0 times longer than proximal depth, straight, with blunt upturned tip, sparsely setose, cutting edge curved, thickened, posterior third covered with minute ventral acute tubercles, distally entire, proximal end with deep depression medially opposing to distal dactylar process; carpus elongate, 0.5 of palm length, 3.0 times longer than central depth, tapering strongly proximally, distodorsal half deeply excavate for reception of posterodorsal palm, unarmed; merus 0.5 of palm length, 3.0 times longer than central depth, feebly bowed, dorsal margin convex, ventral margin straight, with seven small acute tubercles; ischium 0.33 of palm length, 2.6 times longer than distal width, tapering proximally, ventral margin with five small acute tubercles; basis and coxa normal.

Thoracic sternites narrow, unarmed, with median projection posterior to second pereiopod attachments.

Ambulatory pereiopod generally as in paratype female 2. Third pereiopod with dactyl ( Fig. 1 View FIGURE 1 F) similar, unguis fully fused to corpus, tip missing, corpus about 2.0 times longer than proximal depth, ventral margin with strong acute distal accessory tooth, with single small acute tooth proximally; propod ( Fig. 1 View FIGURE 1 E) about 0.37 of CL, 4.2.times longer than proximal depth, tapering slightly distally, with pair of distoventral spines, two ventral spines, and two further ventral spines more proximally (?), other segments as in paratype female 2.

Pleopods of normal shape. First pleopod with endopod ( Fig. 1 View FIGURE 1 G) about 0.5 of exopod length, 3.0 times longer than wide, distally rounded, with seven short setae medially, distal and lateral setae missing. Second pleopod with endopod ( Fig. 1 View FIGURE 1 I) about 0.8 of exopod length, with appendices at 0.33 of medial length, appendix masculina with corpus reduced, forming small medial lobe with three long finely setulose terminal setae ( Fig. 1 View FIGURE 1 I), longest spine 0.4 of endopod length.

Uropods as in paratype female 2. Distolateral exopods ( Fig. 1 View FIGURE 1 J) with six and eight small acute teeth and larger terminal tooth

Paratype female 1, ovigerous, CL 5.2 mm. Generally as specimen below. Both first pereiopods present, second pereiopods and ambulatory pereiopods missing. Rostrum ( Fig. 4 View FIGURE 4 B) acute with single small acute dorsal tooth, with single seta in front of tooth and terminal tooth. Ova 0.6 mm length.

Paratype female 2, post-ovigerous, CL 4.9 mm, lacking both second pereiopods and all except one ambulatory pereiopod.

Rostrum obsolescent, very obliquely obtuse ( Fig. 2 View FIGURE 2 D) in dorsal view, without dorsal tooth, single dorsal seta; carapace ( Fig. 2 View FIGURE 2 A) smooth, compressed, 1.25 times as deep as long, with small rounded antennal angle, acute in lateral view ( Fig. 2 View FIGURE 2 C), without supra-orbital, epigastric and hepatic teeth, anterolateral angle strongly anteriorly produced, rounded.

Abdominal segments smooth; third segment not posterodorsally produced, anterior pleura enlarged, all broadly rounded, fourth and fifth smaller, rounded, sixth segment ( Fig. 2 View FIGURE 2 E) as long as fifth, depressed, twice as wide as long, without posterodorsal angle, posteroventral angle expanded, rounded.

Telson ( Fig. 2 View FIGURE 2 E) about 0.3 of CL, 1.4 times longer than broad, lateral margin convergent, convex, posterior margin broadly rounded, without median process, with two pairs of similar submarginal dorsal spines, about 0.14 of telson length, at 0.15 and 0.6 of telson length, lateral posterior spines ( Fig. 2 View FIGURE 2 F) small, about 0.4 of dorsal spine length, intermediate spines robust, 0.6 of dorsal spine length, submedian spines shorter, about 0.8 of intermediate spine length, non-setulose.

Epistome unarmed.

Antennule ( Fig. 2 View FIGURE 2 H) of normal form, proximal segment 2.0 times longer than wide, medial margin straight, with minute acute denticle at 0.5 of length, distolateral angle with slender acute tooth, lateral margin sinuous, stylocerite acute, statocyst normal with spherical statolith; intermediate and distal segments normal, flagella missing.

Antenna ( Fig. 2 View FIGURE 2 I) with coxopodite with large antennal gland tubercle; basicerite unarmed, carpocerite reaching to proximal end of scaphocerite tooth, subcylindrical, 3.8 times longer than wide, merocerite small, ischiocerite robust; scaphocerite ( Fig. 2 View FIGURE 2 J) well developed, 2.7 times longer than proximal width, tapering strongly distally, lateral margin concave with stout distal tooth, about 0.2 of scaphocerite length, lamella greatly reduced to small rounded distolateral lobe, devoid of setae; flagella missing.

Eye about 0.2 of CL, cornea hemispherical, diameter 0.1 of CL, oblique, well pigmented, without accessory pigment spot; stalk subcylindrical, 2.0 times longer than width.

Thoracic sternites narrow anteriorly, slightly expanding posteriorly, unarmed.

Mandible ( Fig. 3 View FIGURE 3 A) with corpus slender, elongate, without palp ( Fig. 3 View FIGURE 3 C); molar processes ( Fig. 3 View FIGURE 3 BD) greatly reduced, asymmetrical, right subcylindrical, tapering distally to small cylindrical process surrounded by short spinules, left subcylindrical tapering to acute distal point; incisor process ( Fig. 3 View FIGURE 3 E) large, expanded, scaphoid, ovoid in shape with lateral margin convex ending in broad rounded tooth, distomedial margin rounded, feebly angular, with about 16 small acute teeth, fifth to sixth teeth larger, rest diminishing proximally.

Maxillula ( Fig. 3 View FIGURE 3 F) with palp feebly bilobed, lower lobe with small setiferous tubercle; upper lacinia ovoid, dorsal margin convex, distal margin oblique, densely covered with long slender deeply orange coloured simple spinules; lower lacinia robust, with similar spines to upper lacinia distally, more slender spines ventrally.

Maxilla ( Fig. 3 View FIGURE 3 G) with palp simple, compressed, distally rounded, with simple seta half way along medial margin; endite simple, rounded, with about fifteen simple marginal setae distally, medial margin distally concave, proximally convex, non-setose; scaphognathite normal, 4.0 times longer than wide,

First maxilliped ( Fig. 3 View FIGURE 3 H) with slender compressed non-setose palp; basal endite broad, rounded, slightly broader than length, distal and medial margin with long slender deeply orange coloured simple spines, lateral margin with four simple setae; caridean lobe well developed, 3.5 times longer than wide, margins densely setose, exopodal flagellum short with numerous plumose marginal setae; coxal endite angularly produced, with two simple spines, with feebly bi-lobed triangular epipod laterally.

Second maxilliped ( Fig. 3 View FIGURE 3 I) of normal form, dactyl narrow, four times longer than wide, densely covered medially with long slender densely serrulate, deeply orange coloured slender spines; propod broad, distolaterally moderately convex with about ten slender densely serrulate, deeply orange coloured slender spines, longer and stouter than dactylar spines; carpus, ischiomerus and basis normal, exopod with slender flagellum, setae missing; coxa medially produced, non-setose, simple elongate epipod laterally, without podobranch.

Third maxilliped ( Fig. 3 View FIGURE 3 J) with ischiomerus and basis completely fused, combined segment twice as long as proximal width, tapering strongly distally, distal margin about 0.2 of proximal width, lateral margin convex proximally, distally straight, with scattered marginal setae, medial margin straight, sparsely setose; intermediate segment subcylindrical, 4.0 times longer than wide, about 0.3 of proximal segment length, setae missing; terminal segment less than half preterminal segment length, tapering, distally rounded, setae missing; exopod long, slender, reaching beyond middle of penultimate segment length, setae missing; coxa not medially produced, without setae, with large rounded lateral plate; without arthrobranch.

First pereiopods ( Fig. 2 View FIGURE 2 K) short, stout, very robust; chela ( Fig. 2 View FIGURE 2 L) about 0.5 of CL, palm smooth, non-setose, compressed, 1.4 times longer than deep, compressed; dactyl ( Fig. 2 View FIGURE 2 M) 0.65 of palm length, robust, spatulate, cutting edge lateral, stout, rounded swelling proximally, tip tridentate, exceeding fixed finger; fixed finger ( Fig. 2 View FIGURE 2 M) similar to dactyl, 1.4 times longer than proximal depth, tips tridentate ( Fig. 2 View FIGURE 2 N), fingers with sparse groups of long setae, with open gap proximally when closed; carpus 0.9 of palm length, 2.4 times longer than distal width, tapering proximally, distodorsal margin depressed; merus 1.3 times palm length, subcylindrical, slightly bowed, 3.2 times longer than central depth; ischium subequal to palm length, tapering proximally, 3.0 times longer than distal width; basis normal; coxa with rounded distomedial process. Without cleaning setae on palm and carpus.

Second pereiopods missing.

Ambulatory pereiopods mainly missing. One detached pereiopod (fourth?) preserved. Dactyl ( Fig. 2 View FIGURE 2 P) short, compressed, tip missing, about 0.15 of propod length, unguis fully fused to corpus, dorsal margin about 1.3 times distal propod depth, unguial portion about 0.6 of dorsal margin length (approx.), ventral margin straight with well developed slender straight acute anteroverted distal accessory tooth, about 0.5 of unguial length (approx.), with two similar small acute anteroverted denticles proximally, proximal margin unarmed; propod slender, about 0.27 of CL, 4.5 times longer than wide, with pair of unequal similar simple distoventral spines ( Fig. 2 View FIGURE 2 O), longer spine subequal to propod width, ventral margin with two similar smaller spines; proximal segments without special features.

Pleopods without special features; protopod with numerous plumose setae medially and laterally.

Uropods extend well beyond telson, protopod posterolaterally rounded; exopod twice as long as broad, lateral margin convex, strongly ventrally submarginally setose, proximal half entire, distal half with about 8–9 small irregular acute teeth, with small acute distolateral tooth with large curved spine medially ( Fig. 2 View FIGURE 2 G), about 0.2 of exopod length; endopod 0.9 of exopod length, 2.3 times longer than wide.

Paratype female 3, post-ovigerous, CL 4.5 mm. Generally as above. Both first pereiopods present, second pereiopods and ambulatory pereiopods missing. Rostrum ( Fig. 4 View FIGURE 4 C) acutely pointed in lateral view, dorsal carina with five acute teeth, proximal tooth small, four distal teeth minute, with single subterminal distal seta; carapace with anterolateral angle strongly produced, rounded.

Measurements (mms). Holotype male, rostrum and carapace, 2.9; postorbital carapace, 2.8; total body length (approx.), 7.2; minor second pereiopod chela, 1.0; major second pereiopod chela, 5.0.

Etymology. Named after locality of capture, Ashmore Reef, northern Western Australia.

Host. Unidentified sponge host.

Colouration. (From colour photograph, Fig 5 View FIGURE 5 A–C). Body and anterior appendages and caudal fan densely streaked with red-brown striae with narrow transparent separations, first and second pereiopods similar but ischia dotted with red-brown spots.

Systematic position. Three species of the genus Nippontonia are now known, the type species of the genus N. minirostris , N. christellae Fransen, 2013 , and N. ashmoriensis sp. nov. Species can be readily separated by stout robust first pereiopods being present in N. ashmoriensis with the carpus shorter than the chela, versus more slender pereiopods in N. minirostris and N. christellae with the carpus longer than the chela.

The holotype of N. minirostris was noted to be without a dorsal rostral tooth in its original description but Fransen (2013) has reported that a paratype and further specimens from Taiwan do have a small acute dorsal rostral tooth as in N. christellae making this not very useful character for species separation. The specimens of N. ashmoriensis are variable ( Fig. 4 View FIGURE 4 ) in this regard and vary from no dorsal rostral teeth to five dorsal teeth although the four distal teeth are minute.

Remarks. The first pereiopods of N. ashmoriensis are remarkably robust ( Fig. 5 View FIGURE 5 ) and without parallel in the Pontoniinae . The setae of the maxillula, first and second maxillipeds are all a dense orange colour, not noted in other pontoniine shrimps.