Neorhynchoplax chipolini, Hsueh, 2018

Hsueh, Pan-Wen, 2018, A new species of Neorhynchoplax (Crustacea: Decapoda: Brachyura: Hymenosomatidae) from Taiwan, Zootaxa 4461 (3), pp. 350-358 : 351-352

Neorhynchoplax chipolini sp. nov.

FIgS 1A, B , 2A – F , 3A – F

Material examined. HOLOTyPE, MALE (2.5 X 2.3 MM) (NMNS 7878-1), XINgdA HARbOUR (22°50´38.1˝N 120°12´46.7˝E), 29 SEPTEMbER 2017. PARATyPES: 1 MATURE FEMALE, 3 OVIgEROUS FEMALES (SMALLEST 4.4 X 4.3 MM, LARgEST 5.2 X 5.2 MM) (NMNS 7878-2–5), 6 JULy 2017, SAME LOcATION AS HOLOTyPE ; 2 OVIgEROUS FEMALES (3.4–3.9 X 3.3–3.9 MM) (NMNS 7878-6–7), 29 SEPTEMbER 2017, SAME LOcATION AS HOLOTyPE .

Description. CARAPAcE SUbcIRcULAR (RANgE OF L/W RATIO: 0.94–1.09), SURROUNdEd by A dISTINcT RIM, NOT dISRUPTEd AT bASE OF ROSTRUM; dORSAL SURFAcE SMOOTH ANd cONcAVE, dISTINcT cERVIcAL, THORAcIc ANd gASTROcARdIAc gROOVES PRESENT; cERVIcAL gROOVES REAcHINg ANTEROLATERAL MARgINS, THORAcIc gROOVES REAcHINg POSTEROLATERAL bORdER, WITH FOUR dEEP PITS AT jUNcTION OF HEPATIc, PREbRANcHIAL ANd gASTRIc AREAS ANd jUNcTION OF POSTbRANcHIAL ANd cARdIAc AREAS NEAR POSTEROLATERAL bORdER ( FIg. 1A ). ROSTRUM dISTINcTLy TRIdENTATE, LATERAL TEETH TRIANgULAR WITH bLUNT TIP, dIREcTEd ANTERIORLy; MEdIAN TOOTH STyLIFORM, dISTINcTLy bENT dOWNWARdS ( FIg. 1B ). ANTEROLATERAL MARgINS OF cARAPAcE SMOOTH ( FIgS. 1A , 2A ), LINEd WITH NUMEROUS SHORT SETAE; SIdE WALL OF cARAPAcE WITH dISTINcT ANTERIORLy cURVEd TOOTH dIREcTLy AbOVE cOXA OF SEcONd AMbULATORy LEg ( FIgS. 1A , 2B ); INFRAORbITAL TOOTH SHORT, SHARP ( FIgS. 1A , 2A, B ). EyESTALk VISIbLE dORSALLy, cORNEAS LARgE, PIgMENTEd ( FIgS. 1A, B , 2A, B ). THIRd MAXILLIPEd LONgITUdINALLy SLENdER, NOT FULLy cOVERINg bUccAL FIELd WHEN cLOSEd; IScHIUM SHORTER THAN SUbOVATE MERUS; EXOPOd STRAIgHT, TIP REAcHINg TO dISTAL MARgIN OF MERUS, FLAgELLUM LONg, ANTEROMESIAL MARgIN WITH ONE TUbERcLE ( FIg. 2C, D ). CHELIPEdS ELONgATE, SUbEqUAL (IN MALE) TO EqUAL (IN FEMALE); MERUS LONg, UNARMEd; cARPUS SUbOVATE; PROPOdUS SLIgHTLy (IN FEMALE) TO MOdERATELy (IN MALE) INFLATEd, LOWER SURFAcES SMOOTH WITH IRREgULAR MESH-LIkE PATTERN, MARgINS WITH ROWS OF SETAE; dAcTyLUS LONgER THAN PALM, OUTER ANd INNER SURFAcES WITH ScATTEREd PUbEScENcE, dENSER ALONg MARgINS, cUTTINg EdgES OF FINgERS WITH 4 LARgE TEETH, SEVERAL MINUTE TEETH dISTALLy ANd ONE SMALL TOOTH PROXIMALLy, NARROW gAP PRESENT AT bASE OF FINgERS WHEN FULLy cLOSEd ( FIg. 2E, F ). AMbULATORy LEgS SLENdER ( FIg. 1A ); INNER ANd OUTER SURFAcES WITH SEVERAL ScATTEREd LONg SETAE; dISTOdORSAL MARgIN OF IScHIUM WITH ONE SMALL TUbERcLE ( FIg. 3A ); dORSAL ANd VENTRAL MARgINS OF IScHIUM, MERUS, cARPUS ANd PROPOdUS LINEd WITH NUMEROUS VERy SHORT cURVEd SETAE, WITH MANy ScATTEREd LONgER SETAE; dISTOdORSAL MARgIN OF MERUS ANd cARPUS WITH A SMALL TUFT OF SHORT SETAE; dAcTyLUS LATERALLy FLATTEN, FALcATE, UNARMEd, SHARPLy TAPERINg dISTALLy, LATERAL SURFAcES (EXcEPT FOR dISTAL PART) WITH FEW ScATTEREd LONg SETAE, dORSAL ANd VENTRAL MARgINS WITH ONE ROW OF MEdIUM SETAE ANd SEVERAL ScATTEREd LONg SETAE, dISTAL PART gENTLy cURVEd, SURFAcES ANd MARgINS WITHOUT SETAE ( FIg. 3B ). PLEON SUbTRIANgULAR IN MALE, OVATE IN MATURE FEMALE, SURFAcE WITH ScATTEREd SETAE, dENSER ALONg MARgINS; MALE PLEONAL SOMITE 1 SLIgHTLy LONgER ANd NARROWER THAN SOMITE 2, SOMITES 3–5 FUSEd, FUSEd SOMITES cONSTITUTINg AbOUT 60% OF PLEON+PLEOTELSON LENgTH, PLEOTELSON TRAPEzOIdAL ( FIg. 3C ). G1 WITH STOUT bASE, SLIgHTLy bENT, UPcURVEd, TAPERINg gRAdUALLy INTO NARROW dISTAL ENd; AN S-SHAPEd gROOVE PRESENT ON INNER SURFAcE OF G1; MIddLE PORTION OF G1 WITH 2 SLENdER SETAE, SUbdISTAL PORTION OF G1 WITH 3 STOUT SETAE PROcESSES, MEdIAN ONE STRONgEST, LONgEST ( FIg. 3D, E ). FEMALE PLEON OVAL (RANgE OF L/W RATIO: 0.79–1.30), SOMITE 1 SLIgHTLy bROAdER THAN SOMITE 2 ANd AbOUT SAME LENgTH; SOMITES 3–5 FUSEd, WITH LATERAL SUTURES bARELy VISIbLE, cONSTITUTINg AbOUT 80% OF PLEON+PLEOTELSON LENgTH, PLEOTELSON SLIgHTLy cURVEd TOWARd PLEON, bROAd TRIANgULAR, LATERAL MARgINS SLIgHTLy cONcAVE ( FIg. 3F ); EggS LINEd AgAINST INNER SURFAcE OF PLEON ANd INdIVIdUALLy kEPT IN SOckETS ( FIg. 3G ).

Etymology. THE SPEcIES IS dEdIcATEd TO THE MEMORy OF MR. CHI PO-LIN (27 DEcEMbER 1964 – 10 JUNE 2017) AERIAL PHOTOgRAPHER ANd dOcUMENTARy FILM dIREcTOR WHO MAdE AN IMMENSE cONTRIbUTION TO ENVIRONMENTAL PROTEcTION IN TAIWAN.

Distribution. ONLy kNOWN FROM THE TyPE LOcALITy.

Remarks. OF THE 10 SPEcIES OF Neorhynchoplax HAVINg UNARMEd AMbULATORy dAcTyLI, FIVE HAVE A TOOTH ON THE POSTEROLATERAL MARgINS OF THE cARAPAcE AS IN N. chipolini sp. nov. THESE ARE N. attenuipes , N. falcifera , N. sinensis , N. tuberculata , ANd N. venusta ( KEMP 1917: 258, FIg. 6; CHOPRA & DAS 1930: 423, TEXT-FIg. 10; SHEN 1932: 59, TEXT- FIg. 33; DAI & YANg 1991: 117, FIg. 60; TAkEdA & MIyAkE 1971: 158, FIg. 1A ; PRETzMANN 1975: 607, PL. 1, FIgS 1 , 2 ; LUcAS 1980: 240, FIg. 3I ; LUcAS & DAVIE 1982: 404, FIg. 1 ; NARUSE et al. 2008: 439, FIg. 7A; Ng 2015: 195, FIgS 1A , 2A ).

Neorhynchoplax falcifera , HOWEVER, dIFFERS FROM N. chipolini sp. nov. IN HAVINg THE MEdIAN ANd LATERAL FRONTAL LObES UPTURNEd ( FIg. 1A, B ) (versus LATERAL LObES dIREcTEd ANTERIORLy WITH THE MEdIAN TOOTH bENT dOWNWARdS) (NARUSE et al. 2008: 439, FIg. 7b).

Neorhynchoplax attenuipes ANd N. tuberculata bOTH POSSESS dISTINcT TUbERcLES ON THE gASTRIc ANd cARdIAc REgIONS OF THE cARAPAcE ( CHOPRA & DAS 1930: 420, 423, TEXT-FIgS. 6, 7, 10), A FEATURE AbSENT IN N. chipolini sp. nov. ( FIgS. 1A , 2A, B ).

Neorhynchoplax sinensis FROM MAINLANd CHINA HAS A HORIzONTALLy PROTRUdEd MEdIAN ROSTRAL TOOTH ANd THE cERVIcAL gROOVES ARE cOMPLETELy cONNEcTEd ON THE ANTERIOR cARAPAcE ( SHEN 1932: 59, TEXT-FIg. 33), WHEREAS N. chipolini sp. nov., HAS THE MEdIAN ROSTRAL TOOTH bENT dOWNWARdS ANd cERVIcAL gROOVES NOT cONNEcTEd ON THE ANTERIOR cARAPAcE ( FIg. 1A, B ). UNLIkE N. chipolini sp. nov., N. sinensis HAS NO TUbERcLE ON THE INNER ANTEROLATERAL MARgIN OF THE FIRST EXOPOd ARTIcLE OF THE THIRd MAXILLIPEdS (NARUSE, PERS. cOMM.; FIg. 2C, D ). MOREOVER, N. chipolini sp. nov. HAS 2 SETAE IN THE MIddLE PART OF THE G1 ( FIg. 3D, E ), bUT THAT OF N. sinensis IS bARE ( SHEN 1932: 61, TEXT-FIg. 36b).

Neorhynchoplax chipolini sp. nov. IS SIMILAR TO N. venusta , dEScRIbEd FROM SINgAPORE, IN THE PRESENcE OF A TRIdENTATE ROSTRUM, THE PRESENcE OF A POSTEROLATERAL cARAPAcE TOOTH dIREcTLy AbOVE THE bASE OF SEcONd AMbULATORy LEg ANd WITH ELONgATE AMbULATORy LEgS. Neorhynchoplax chipolini sp. nov., HOWEVER, HAS SMOOTH ANTEROLATERAL MARgINS OF THE cARAPAcE ( FIgS. 1A , 2A ) (versus WITH A SMALL TOOTH IN N. venusta ; Ng 2015: 193, FIg. 2A ); A MEdIAN ROSTRAL TOOTH THAT IS STyLIFORM ANd dISTINcTLy bENT dOWNWARdS ( FIg. 1A, B ) (versus SPATULIFORM, bROAdEST AbOUT HALFWAy ALONg ITS LENgTH ANd bROAdLy ROUNdEd APIcALLy IN N. venusta ; Ng 2015: 193, FIg. 2A ); ANd THE ANTERO-MESIAL MARgIN OF THE EXOPOd OF THE THIRd MAXILLIPEd HAS ONE TUbERcLE ( FIg. 2C, D ) (versus SMOOTH ANd UNARMEd IN N. venusta ; Ng 2015: 195, FIg. 2B ).

Reproductive biology. LUcAS (1980) NOTEd THAT SEVERAL SPEcIES OF Neorhynchoplax (AS Elamenopsis ) HAVE EggS SMALLER THAN 0.3 MM dIAMETER. THE EggS OF Neorhynchoplax chipolini sp. nov. ARE LARgER (0.43±0.02 MM, N=6, PARATyPE NMNS7878-5), ALTHOUgH IT cARRIES AS MANy EggS (cARAPAcE WIdTH 4.3 MM, 76 EggS) IN ONE bROOd AS N. aspinifera (cARAPAcE WIdTH 3.0 MM, 77 EggS) ( LUcAS 1980: 216). IT IS WORTH MENTIONINg THAT EggS OF N. chipolini sp. nov., WHIcH ARE LINEd AgAINST THE INNER SURFAcE OF AbdOMEN, ARE INdIVIdUALLy kEPT IN SOckETS ( FIg. 3G ). THIS PROTEcTIVE STRUcTURE WAS ALSO ObSERVEd IN N. mangalis (Ng, 1988) ANd N. yaeyamaensis (cF. Ng & CHUANg 1996: 60, FIgS. 26A–E; NARUSE et al. 2005: 3, FIg 1E ). Ng et al. (1999) NOTIcEd FEMALES OF N. sinensis cARRy LARgE EggS ANd SUggESTEd THEy MAy ALSO bE OVOVIVIPAROUS AS ARE FEMALES OF N. mangalis (Ng et al. 1999: 91) .

Ecology. OF THE gENERA OF HyMENOSOMATIdAE , Neorhynchoplax APPEARS TO HAVE THE HIgHEST NUMbER OF SPEcIES ASSOcIATEd WITH FRESHWATER OR bRAckISH WATER HAbITATS. LUcAS (1980) REVIEWEd SPEcIES IN TEN gENERA ANd NOTEd Elamenopsis A. MILNE-EdWARdS, 1873 , TO HAVE THE HIgHEST NUMbER OF SPEcIES (11) INHAbITINg ENVIRONMENTS WITH LOW SALINITy. BUT 15 OF THE 17 VALId SPEcIES HAVE SINcE bEEN TRANSFERREd TO Neorhynchoplax . THE 14 NEW MEMbERS dEScRIbEd SINcE 1980 cONFIRM LUcAS’S cONcLUSION. OF 33 cURRENTLy kNOWN SPEcIES OF Neorhynchoplax , 28 HAVE bEEN REPORTEd FROM FRESHWATER ANd bRAckISH WATER HAbITATS. EXcEPTIONS ARE N. bai NARUSE, MENdOzA & Ng, 2008 , N. chipolini sp. nov., N. falcifera , N. okinawaensis , N. sinensis , ANd N. venusta , WHIcH HAVE SO FAR ONLy bEEN FOUNd IN MARINE HAbITATS ( TAbLE 1).

Figures

FIGURE 1. Neorhynchoplax chipolini sp. nov. A, Holotype male (NMNS 7878-1), habitus; arrows indicate locations of deep pits on carapace, all pubescence and setae on carapace and appendages not shown. B, paratype female (NMNS 7878-5), closeup frontal view of the rostral area; arrow indicates downward bent median rostral tooth. Scale: A, 1.0 mm; B, 0.5 mm.

FIGURE 2. Neorhynchoplax chipolini sp. nov. A, C–F, paratype female (NMNS7878-5); B, paratype female (NMNS7878-3). A, anterior carapace, dorsal view, white arrow indicates the smooth anterolateral margin; B, posterolateral tooth of carapace (white arrow), and location of deep pits on carapace (black arrows); C, right third maXilliped, eXternal view; arrow indicates the anteromesial tubercle of eXopod (setae not shown); D, close-up of the distal end of eXopod of right third maXilliped, arrow indicates the anteromesial tubercle; E, right cheliped, inner face; F, right cheliped, outer face. Scale: A, C, 0.5 mm; B, E–F, 1.0 mm; D, 0.05 mm.

FIGURE 3. Neorhynchoplax chipolini sp. nov. A, B, F, paratype female (NMNS7878-2); C–E, holotype male (NMNS7878-1); G, paratype female (NMNS7878-5); all pubescence and setae were not shown. A, ischium of the 4 th ambulatory leg, dorsal view, arrow indicates the distal tubercle; B, dactylus of the 4 th ambulatory leg, dorsal view; C, male pleon; D, photomicrograph of right G1; E, line drawing of right G1; F, non-ovigerous female pleon, dashed lines indicate rudimentary sutures; G, ovigerous female pleon, arrows indicate the rim of egg sockets. Scale: A, 0.2 mm; B–C, F–G, 0.5 mm; D–E, 0.1 mm.