Periclimenoides tyrannodentatus, Šobáňová & Lin & Ďuriš, 2017

Šobáňová, Anna, Lin, Chia-Wei & Ďuriš, Zdeněk, 2017, Periclimenoides tyrannodentatus, a new species of symbiotic shrimps (Crustacea: Decapoda: Palaemonidae) from Taiwan, Zootaxa 4363 (2), pp. 281-290 : 282-288

publication ID	https://doi.org/ 10.11646/zootaxa.4363.2.7
publication LSID	lsid:zoobank.org:pub:40339F7A-E1CA-4C38-91B1-572884797B87
DOI	https://doi.org/10.5281/zenodo.6000655
persistent identifier	https://treatment.plazi.org/id/0384B825-FF91-FF8A-9AF8-FDBBC56289BE
treatment provided by	Plazi
scientific name	Periclimenoides tyrannodentatus
status	sp. nov.

Treatment

Periclimenoides tyrannodentatus View in CoL sp. nov.

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

Type material. Holotype: female PoCL 3.2 mm (NMMBCD 4053), Hojie , 21° 57’ 20.4" N, 120° 42’ 41.4" E, Pingtung County, Taiwan, 23 Sep. 2011, depth 15–17 m, from unidentified sponge, coll. C.- W. Lin (fcn 20110923). Description. Small sized shrimp of subcylindrical body form, glabrous, slightly pitted ( Figs 1 View FIGURE 1 , 2 View FIGURE 2 ). GoogleMaps

Rostrum ( Fig. 2A View FIGURE 2 ) about 0.35 of PoCL, well developed, slender, compressed, extending to level of distal end of basal segment of antennular peduncle. Rostrum dorsally dentate, rostral dentition 4/0. Proximal tooth situated anteriorly to posterior orbital margin, teeth directed anteriorly, diminishing in size distally. Ventral margin simple, nearly straight, tip of rostrum acute.

Carapace ( Figs 1 View FIGURE 1 , 2A View FIGURE 2 ) compressed, 1.2 times as long as broad, without hepatic tooth. Orbits well developed, without supraorbital spines, inferior orbital angle distinct, obsolete. Antennal tooth well developed, strong, acute, placed marginally. Anterolateral margin of carapace broadly rounded, not produced.

First pleonal segment without anterodorsal median lobe. Five anterior pleura ( Fig. 1 View FIGURE 1 ) rounded, fourth and fifth ones posteriorly produced. Dorsal length of fifth and sixth segments subequal, latter with posterolateral angles subtriangular, subacute, posteroventral angles projecting into distinct rounded lobe.

Telson ( Fig. 2C View FIGURE 2 ) about 1.8 times sixth pleonal segment length, 0.5 of PoCL, broad, about 1.7 times longer than maximal telson width. Lateral margins convex, posteriorly convergent. Dorsal surface convex, bearing two pairs of well developed dorsal spines, both situated in proximal half of telson—at about 0.14 and 0.45 of telson length from anterior margin; anterior pair similar in size to posterior pair, 0.16–0.20 of telson length. Posterior margin (including lateral spines) about 0.45 of anterior telson width, broadly convex, with three pairs of spines ( Fig. 2D View FIGURE 2 ), without median projection. Lateral spines small, about 0.3 of intermediate spine length, and placed distinctly anteriad from bases of intermediate and submedian spines; intermediate spines stout, long, about 0.23 of telson length. Submedian spines slightly shorter and more slender than intermediate ones, setulose on sides.

Eyes ( Fig. 2B View FIGURE 2 ) well developed and pigmented, with globular cornea situated obliquely on stalk. Small accessory pigment spot present dorsally on posterior margin of cornea. Corneal diameter about 0.15 of PoCL. Corneal length about 0.6 of corneal diameter. Stalk short, medial length subequal to corneal diameter, slightly swollen proximally.

Antennule ( Fig. 2B View FIGURE 2 ) with peduncle well exceeding carpocerite and rostrum, basal segment of antennular peduncle broad posteriorly, about 2.6 times as long as central width. Outer margin slightly concave, blunty angular proximally, slightly tapering distally, terminating in small, acute distolateral tooth. Distolateral tooth overreaching anterior margin of basal segment of antennular peduncle and reaching to middle of intermediate segment. Anterior margin setose, inner margin straight, with distinct ventro-medial tooth. Stylocerite short, leaf-like, distally acute, reaching almost to halflenght of basal antennular segment length. Statocyst normal. Intermediate and distal segments short, robust and subequal, together measuring about 0.4 of proximal segment length. Flagella short, upper flagellum biramous, stout, with fused part consisting of 4–5 articles; short ramus with 2 articles; 6–9 groups of aesthetascs present; longer ramus filiform; lower flagellum simple, filiform, with about 18 slender segments with combined length about 0.5 of PoCL.

Antenna ( Fig. 2B View FIGURE 2 ) of normal form, with antennal flagellum filiform. Basicerite short, laterally and dorsally unarmed. Carpocerite of antennal peduncle subcylindrical, short, reaching to about 0.66 of scaphocerite length, about 4 times longer than broad. Scaphocerite reaching distal end of antennular peduncle, more than twice as long as broad, oval, broader anteriorly; lateral margin straight; anterior margin of lamella rounded, exceeding lateral tooth.

Mouthparts ( Fig. 3 View FIGURE 3 ) from left side dissected.

Mandible ( Fig. 3A View FIGURE 3 ) without palp, incisor process well developed, slender, with 3 acute teeth apically (3 teeth also on right mandible). Molar process elongate, slightly tapering distally, apex obliquely cut, subquadrate, occlusal surface covered with dense brush of short blunt setae and numerous more slender and acute setae on sides ( Fig. 3B View FIGURE 3 ).

Maxillule ( Fig. 3C View FIGURE 3 ) with short palp, lower palp lobe broader, with slender simple seta, upper lobe thin. Upper lacinia broad, slightly longer than broad, distal margin convex, with 7 long and slender nonarticulated teeth followed with tuft of sparse simple setae. Lower lacinia short, slender, tapering distally, with distal margin bearing group of long terminal and subterminal setae.

Maxilla ( Fig. 3D View FIGURE 3 ) with elongate slender palp slightly shorter than basal endite, with feebly bilobed apex. Basal endite deeply bilobed distally, apices rounded, with 7 and 4 long slender setae on distal and proximal apices, respectively. Coxal endite indistinct, obsolete. Scaphognathite well developed, elongate, about 3.7 times longer than central width, lined with short marginal plumose setae.

Exopod of first maxilliped ( Fig. 3E View FIGURE 3 ) well developed, with flagellum compressed, wrinkled, bearing 4 plumose terminal and 3 subterminal setae. Caridean lobe well developed, with lateral margin slightly convex, distally rounded, marginal setae plumose. Palp elongate, about 5 times longer than central width, exceeding anterior margin of basal endite; palp tapering distally, with rounded apex carying pair of preterminal plumose setae. Basal endite with distal margin rounded, medial margin straight, with numerous slender setae, coxal endite divided from basal endite by shallow emargination, with few slender setae. Epipod deeply bilobed.

Second maxilliped ( Fig. 3F View FIGURE 3 ) stout, with normally developed endopod. Dactylar segment of endopod broad, about 2 times longer than maximal width, distomedial margin straight, covered with numerous serrulate setae, propodal segment normal, ovate, distomedial margin not produced, convex, with several slender setae. Carpus broad, with irregularly lobate distal margin, merus strong, broad, ischium fused to basis, segments short, feebly demarcated, without special features. Coxa medially produced, rounded, bearing pair of setae. Exopod normally developed, with flagellum as in first maxlliped. Epipod stout, elongate, simple, without podobranch.

Third maxilliped ( Fig. 3G View FIGURE 3 ) normally developed. Coxa with small, reduced, unilamellate arthrobranch. Lateral lobe large, broadly rounded. Basis broadly rounded medially, fused with ischiomerus, suture feebly demarcated. Ischiomerus about 2.2 times longer than basal width, with row of over 10 serrulate setae distally along medial margin. Penultimate segment about 0.5 of ischiomerus and basis length combined, about 3.5 times longer than wide, with medial row of serrulate setae. Terminal segment stout, tapering distally, about 0.6 of penultimate segment length, with several medioventral rows of serrulate setae. Exopod well developed, reaching to level of distal margin of penultimate segment, with flagellum as in first and second maxillipeds.

First pereiopods ( Fig. 4A–F View FIGURE 4 ) moderately slender, overreaching carpocerite by distal half of merus. Chela stout, with palm short, as long as deep, slightly compressed, dorsal margin convex, ventral border straight. Fingers about 1.3 times longer than palm, occupying about 0.6 of chela length, broad and high basally, feebly subspatulate laterally, tapering strongly distally to hooked tips crossing one another when chela closed. Fingers provided with transverse rows of setae on outer margin. Movable finger about 3.2 times longer than basal width, slightly curved, laterally bearing outwards expanded and finely pectinate lamella extending along whole length of dactylus ( Fig. 4B–D, F View FIGURE 4 ); cutting edge of movable finger obsolete. Fixed finger about 2.5 times longer than basal width, cutting edge broad, entire. Carpus subcylindrical, tapering proximally, about 5 times longer than central width, about 1.3 times longer than chela, subequal to merus. Merus of normal form, about 3.7 times longer than central width, tapering both distally and proximally, with length subequal to carpus length, unarmed. Ischium short, about 0.4 of merus length, unarmed. Basis and coxa stout, short, without special features.

Second pereiopods ( Figs 4G, H View FIGURE 4 ; 5A, B) well developed, unequal, chelae dissimilar in shape.

Major second pereiopod chela ( Figs 4G View FIGURE 4 ; 5A) swollen and robust, about 1.1 times PoCL and 1.3 times minor chela length. Palm moderately compressed, oval in section, tapering distally, palmar surface smooth, glabrous, almost 2.5 times longer than deep. Fingers without molar process and fossa, compressed, dactylus occupying distal 0.25 of chela length, longer than fixed finger; tips crossed over when chela closed. Dactylus aproximately 4.5 times longer than maximum depth, dorsal margin broadly convex, apex blunty hooked; cutting edge proximally with two rounded incisions with one acute tooth between them; distal 2/3 of dactylus feebly concave ventrally, with cutting edge uniformly denticulate by about 35 small acute teeth ( Fig. 5A View FIGURE 5 ). Fixed finger distinctly shorter than movable finger, slightly tapering distally, tip broken in holotype; proximal part of cutting edge forming higher ridge bearing series of 5 blunt teeth separated by rounded notch from lower distal 2/3 of cutting edge; latter cutting margin feebly concave, covered by row of over 30 small acute denticles, these slightly smaller than those on dactylus. Carpus terminally articulated with propodus, unarmed, about 0.3 of palm length, 1.5 times longer than distal width, expanded distally and tapering proximally. Merus unarmed, about 0.6 of palm length, 3.5 times longer than central width, slightly tapering proximally. Ischium slightly shorter than merus, about 3.5 times longer than distal width, tapering slightly proximally, unarmed. Basis and coxa slender, without special features.

Minor second pereiopod ( Fig. 4H View FIGURE 4 , 5B View FIGURE 5 ) dissimilar to major second pereiopod, with chela smaller, about 0.9 of PoCL and 0.8 of major chela length. Palm long, smooth, glabrous, oval in section, about 2.4 times longer than deep, slightly swollen proximally and faintly tapering distally. Fingers strongly compressed and about 0.6 of palm length, occupying distal third of chela length, distal margins broadly rounded, with terminal teeth hooked. Dactylus straight, highest at distal third of length, with dorsal margin moderately convex, length about 3.3 times of maximal depth; dactylar apex broadly rounded, with sharp hooked tip exceeding distal end of fixed finger; cutting edge with three low triangular teeth proximally (second one largest), distal half of cutting edge denticulate with about 30 denticles, latter minute proximally but increasing in size distally, distal series of about last 10 denticles composed of strongest and acute teeth situated along convexly produced distoventral margin ( Fig. 5B View FIGURE 5 ). Fixed finger shorter than dactylus, compressed, straight and uniformly high, 3 times longer than basal width; proximal part of cutting edge entire, with one sharp triangular tooth on proximal third; distal half of cutting edge similar to that of dactylus, with about 30 denticles, latter minute proximally, distal half of denticulation with minute denticles increasing in size distally, subterminal ones largest and acute, distributed along convexly produced distodorsal margin, apex terminating in strong tooth turned upwards. Carpus unarmed, terminally articulated with propodus, about 0.6 of palm length, 2.5 times longer than distal width, excavate distally and tapering proximally. Merus unarmed, about 0.75 of palm length, 3.3 times longer than central width, tapering slightly proximally and distally. Ischium unarmed, slightly shorter than merus, 3.7 times longer than distal width. Basis and coxa slender, without special features.

Ambulatory pereiopods ( Fig. 5C–E View FIGURE 5 ) moderately slender, with stout simple dactyli. Dactylus of third pereiopod about 0.16 of propodus length, corpus compressed, tapering distally, unarmed ventrally, about 2 times longer than proximal width; dorsal border feebly convex, almost straight; unguis distinctly demarcated from corpus, stout, simple, curved downwards, about 0.5 of corpus length, and 2.1 times longer than own proximal width. Propodus about 0.3 of PoCL, compressed, 5.5 times longer than dactylus length, about 7 times longer than maximal width, slightly tapering distally, distal width about 0.7 of maximal width; ventral border straight, distoventral angle armed with pair of short spines about 0.4 of dactylus length, and two slender single spines placed more proximally on ventral margin at about 0.8 and 0.45 of propodus length from proximal end; carpus about 0.85 of propodus length, stout, 4.8 times longer than maximal width, broadening distally, unarmed. Merus robust, about 1.3 times propodus length, 4.6 times longer than central width, subcylindrical, compressed, tapering proximally and distally, unarmed. Ischium equal to 0.85 of propodus length, 3.5 times longer than distal width, tapering proximally. Basis and coxa slender, without special features.

Uropodal protopodite ( Fig. 2C View FIGURE 2 ) with acute lateral lobe, posterolaterally unarmed. Exopod distally overreaching telson, broad, ovate, about 1.5 times longer than wide, lateral margin of exopod broadly convex, setose, with acute distolateral tooth and larger movable spine medially ( Fig. 2E View FIGURE 2 ); exopod without distinct diaeresis. Endopod of approximately same length as exopod, ovate, two times longer than broad.

Measurements. Holotype total body length 11.8 mm; postorbital carapace length (PoCL) 3.2 mm; carapace with rostrum length 4.3 mm; second pereiopod major chela length 3.5 mm; minor chela length 2.8 mm.

Coloration. Unknown.

Host. Unidentified sponge; both known congeners were also previously reported as associated with sponges ( Fujino & Miyake, 1968; Bruce 1981, 1983).

Etymology. The species name is combined from ‘Tyrannosaurus ‘ to point on some resemblance of the dentition of the second pereiopod minor chela with jaws of that most popular predatory dinosaur, and the Latin ‘ dente ‘, tooth.

Distribution. The present species is currently only known from the type locality in southwestern Taiwan.