Refining the genus Rochinia A. Milne-Edwards, 1875: reinstatement of Scyramathia A. Milne-Edwards, 1880 and Anamathia Smith, 1885, and a new genus for Amathia crassa A. Milne-Edwards, 1879, with notes on its ontogeny (Crustacea: Brachyura: Epialtidae) Author Tavares, Marcos Author Santana, William text Zootaxa 2018 4418 3 201 227 journal article 30117 10.11646/zootaxa.4418.3.1 e3885b72-41b7-4aed-996f-4ad59ae7023d 1175-5326 1244854 7E1693CB-B902-422F-9C5E-C1A0FCEA809C Minyorhyncha n. gen. Type species. Amathia crassa A. MILNE-EDWARDS, 1879 , by pRESENT DESIGNATION. GENDER fEmININE. Included species. MONOTypIC: Minyorhyncha crassa (A. MILNE-EDWARDS , 1879) , n. gen ., n. comb . [ Amathia ] (WA). Diagnosis. (BASED ON FULLy DEVELOPED SPECIMENS)—ROSTRAL SPINES SHORT, ALMOST STRAIGHT. CARAPACE DISTINCTLy SUBCIRCULAR IN OUTLINE, DORSAL SURFACE REMARKABLy VAULTED, PARTICULARLy SWOLLEN AT PROTOGASTRIC, BRANCHIAL REGIONS. SIX SPINES ALONG DORSAL MIDLINE OF CARAPACE: MESOGASTRIC, METAGASTRIC, UROGASTRIC, 2 CARDIAC, INTESTINAL. BRANCHIOSTEGAL REGION WITH ROW OF STRONG, ACUTE SPINES ALONG MOST OF POSTEROINFERIOR HALF OF LINE OF DEHISCENCE. TRANSVERSE ROW OF STRONG, ACUTE SPINES EXTENDING SUBPARALLELy ALONG POSTERIOR MARGIN OF CARAPACE RUNNING ACROSS INTESTINAL REGION. ANTENNAL SEGMENT 2+3 WITH ONE ANTERO-VENTROLATERAL, ONE POSTERO-VENTROLATERAL, NEARLy EQUAL IN SIZE, STRONG SPINES. TWO EQUALLy LARGE PLEUROBRANCHS ON THORACIC SOMITE 3 (MXP3), ONE LARGE PLEUROBRANCHIA ON THORACIC SOMITE 2 (MXP2). MALE THORACIC STERNITES 4–7 WITH ONE, STRONG, TRANSVERSE RIDGE EACH. MALE THORACIC STERNITE 8 EXTENDING LATERALLy BEyOND STERNO-ABDOMINAL CAVITy, STERNITE LEFT UNCOVERED LATERALLy By ABDOMEN, VISIBLE IN VENTRAL VIEW. MALE CHELIPED SLENDER, EXTREMELy LONG, MUCH LONGER THAN P2. P5 COXO-PLEURAL GyNGLyME HIDDEN By THE CARAPACE. MALE ABDOMINAL SOMITES 1 AND 2 WITH STRONG, ACUTE, AXIAL SPINE EACH (SMALLER IN FEMALES). G1 REACHING FAR BEyOND THORACIC STERNAL SUTURE 4/5, RATHER STRAIGHT PROXIMALLy AND MEDIALLy, DISTINCTLy CURVED INWARDS SUBDISTALLy, CONVERGENT ANTERIORLy, TAPERING TO BLUNT TIP, LATERAL MARGINS GENTLy CURVED INWARDS DISTALLy, KEEL ABSENT ( FIGS. 13I , J , 14A). G2 SHORT, ABOUT AS LONG AS 1 /5 OF TOTAL LENGTH OF G1 (FIG. 14A–D). FOR CHANGES DURING ONTOGENy SEE "REMARKS". Remarks. Minyorhyncha n. gen . CAN BE EASILy DISTINGUISHED FROM Rochinia A. MILNE-EDWARDS, 1875 S. STR. (REPRESENTED By ITS TyPE SPECIES Rochinia gracilipes A. MILNE-EDWARDS, 1875 ), By A UNIQUE SET OF CHARACTERS, WHICH INCLUDES: 1) DRAMATIC CHANGES IN MORPHOLOGy OVER ONTOGENy ( FIGS. 4A–D , 5A–D , 6A–D , 8 )—SEE ALSO "NOTES ON ONTOGENy" UNDER M. crassa n. gen., n. comb. , VS ONLy SLIGHT CHANGES IN MORPHOLOGy OVER ONTOGENy AS BOTH, DEVELOPING AND FULLy DEVELOPED SPECIMENS (E.G., CL 6 MM AND CL 18.5 MM, RESPECTIVELy) ARE SIMILAR IN MORPHOLOGy IN Rochinia S. TR.; 2) IN FULLy DEVELOPED SPECIMENS CARAPACE DISTINCTLy SUBCIRCULAR IN OUTLINE, DORSAL SURFACE REMARKABLy VAULTED, PARTICULARLy SWOLLEN AT THE PROTOGASTRIC AND BRANCHIAL REGIONS ( FIGS. 4D , 5D , 6A , 8 , 11B , 12D ), VS. CARAPACE DISTINCTLy PIRIFORM, RATHER LOW AND FLATTENED, SLIGHTLy HIGHER ALONG THE DORSAL MIDLINE OF THE CARAPACE IN Rochinia S. STR. ( FIGS. 2A, F , 9D , 11A , 12A ); 3) MALE THORACIC STERNITE 8 EXTENDING LATERALLy BEyOND THE STERNO- ABDOMINAL CAVITy, SO THAT IT IS LEFT UNCOVERED LATERALLy By THE ABDOMEN AND THUS VISIBLE IN VENTRAL VIEW ( FIGS. 6B , 7C, D , 10C, D ), VS. STERNITE 8 RESTRICTED TO THE STERNO-ABDOMINAL CAVITy, SO THUS CONCEALED By THE ABDOMINAL SOMITES AND THEREFORE NOT EXPOSED VENTRALLy IN Rochinia S. STR. ( FIGS. 2C , 10A, B ); 4) P5 COXO-PLEURAL GyNGLyME HIDDEN By THE CARAPACE ( FIG. 10B ), VS. COXO-PLEURAL GyNGLyME EXPOSED IN LATERAL VIEW IN Rochinia ( FIG. 10A ); 5) MALE THORACIC STERNITES 4–7 WITH ONE STRONG TRANSVERSE RIDGE EACH ( FIG. 7C ), VS. NO THORACIC STERNAL TRANSVERSE RIDGES IN Rochinia ( FIG. 2C ); 6) TWO EQUALLy LARGE PLEUROBRANCHIAE IN THE THORACIC SOMITE 3 (MXP3), VS. PLEUROBRANCHIAE STRONGLy UNEQUAL, THE ANTERIORMOST BRANCHIA REDUCED IN SIZE IN Rochinia S. STR. ; 7) ONE LARGE PLEUROBRANCH ON THORACIC SOMITE 2 (MXP2), VS. NO PLEUROBRANCH ON THORACIC SOMITE 2 IN Rochinia S. STR. FOR ADDITIONAL DETAILS ON THE BRANCHIAL FORMULAS SEE TABLE 1; 8) G1 REACHING FAR BEyOND THE THORACIC STERNAL SUTURE 4/5, RATHER STRAIGHT PROXIMALLy AND MEDIALLy, DISTINCTLy CURVED INWARDS SUBDISTALLy, TAPERING TO BLUNT TIP ( FIGS. 13I , J , 14A), VS. G1 STRAIGHT, REACHING AT MOST SLIGHTLy BEyOND THE SUTURE 4/5, TAPERING PROGRESSIVELy TO SHARP TIP IN Rochinia S. STR. ( FIG. 13G, H ); 9) SIX SPINES ALONG THE DORSAL MIDLINE OF THE CARAPACE: MESOGASTRIC (SOMETIMES DOUBLED), METAGASTRIC, UROGASTRIC, 2 CARDIAC, INTESTINAL ( FIGS. 4C, D , 5A–D , 6A , 11B, 11D ), VS. DORSAL MIDLINE OF THE CARAPACE WITH 3 DISTINCT BULGES IN Rochinia S. STR. : METAGASTRIC, CARDIAC, AND INTESTINAL ( FIGS. 2A , 9D , 11A , 12A ); 10) MALE ABDOMINAL SOMITES 1 AND 2 WITH ONE STRONG, ACUTE, AXIAL SPINE EACH—SMALLER IN THE FEMALES ( FIG. 6D ), VS. MALE ABDOMINAL SOMITE 1 WITH ONE SMALL AXIAL KNOB, MALE SOMITE 2 AND FEMALE SOMITES 1 ND 2 SMOOTH IN Rochinia S. STR. ( FIG. 2F ); 11) CARAPACE BRANCHIOSTEGAL REGION WITH A ROW OF STRONG, ACUTE SPINES ALONG MOST OF THE POSTEROINFERIOR HALF OF THE LINE OF DEHISCENCE ( FIGS. 5C, D , 11B ), VS. ROW OF SPINES LACKING IN Rochinia S. STR. ( FIG. 10A ); 12) MALE CHELIPEDS SLENDER, EXTREMELy LONG, MUCH LONGER THAN P2 IN FULL GROWN SPECIMENS ( FIG. 8 ), VS. CHELIPEDS DISTINCTLy MASSIVE, SHORT, MUCH SHORTER THAN P2 IN Rochinia S. STR. ( FIGS. 2A, B , 9D ); 13) ROSTRUM SHORT RELATIVE TO CARAPACE LENGTH IN FULLy DEVELOPED MALES ( FIGS. 4D , 5D , 8 , 11B ), VS. ROSTRUM DISTINCTLy LONGER IN FULLy DEVELOPED MALES IN Rochinia S. STR. ( FIGS. 2A , 8D , 11A ); 14) TRANSVERSAL ROW OF STRONG, ACUTE SPINES EXTENDING SUBPARALLELy ALONG THE POSTERIOR MARGIN OF THE CARAPACE AND RUNNING ACROSS THE INTESTINAL REGION ( FIGS. 5D , 6D , 11B ), VS. TRANSVERSE ROW OF SPINES ABSENT IN Rochinia S. STR. ( FIGS. 2A, E, F , 11A ); 15) ANTENNAL SEGMENT 2+3 WITH ONE ANTERO-VENTRO-LATERAL AND ONE POSTERO- VENTRO-LATERAL, SUBEQUAL, STRONG SPINES ( FIGS. 5C, D , 6B , 7C, D , 9B , 11B ), VS. ANTERO-VENTRO-LATERAL SPINE SHORT AND POSTERO-VENTRO-LATERAL LACKING IN Rochinia S. STR. ( FIGS. 2B, D , 11A ). Minyorhyncha n. gen. AND Scyramathia BOTH UNDERGO DRAMATIC CHANGES IN MORPHOLOGy OVER ONTOGENy (SEE "REMARKS" BELOW UNDER Scyramathia AND M. crassa n. gen., n. comb. AND ALSO TAVARES et al . 2015 FOR S. umbonata , AS Rochinia umbonata ). AS PREVIOUSLy MENTIONED IN Rochinia S. STR. AND Anamathia S. STR. DEVELOPING AND FULLy DEVELOPED SPECIMENS HAVE SIMILAR MORPHOLOGy. FULLy DEVELOPED SPECIMENS OF Minyorhyncha n. gen. AND Scyramathia DIFFER FROM EACH OTHER IN HAVING: 1) THE CARAPACE DISTINCTLy SUBCIRCULAR IN OUTLINE, DORSAL SURFACE REMARKABLy GLOBOSE, PARTICULARLy SWOLLEN AT THE PROTOGASTRIC AND BRANCHIAL REGIONS AND STRONGLy SPINOSE ( FIGS. 4D , 5D , 6A , 8 , 11B , 12D ), VS. CARAPACE DISTINCTLy PEAR-SHAPED; SUPRAORBITAL, PREORBITAL, HEPATIC, MESOGASTRIC, PROTO-, MESO- AND METABRANCHIAL, CARDIAC, AND INTESTINAL TUBERCLES SHOWING AS VERy LARGE, FLAT-TOPPED, LEAF-LIKE PLATES WHOSE CIRCUMFERENCES ARE BROADER THAN THE STEM IN Scyramathia ( FIG. 1B–D ); 2) PREORBITAL SCUTELLATE PLATE AND HEPATIC SPINE NOT FUSED TOGETHER ( FIGS. 4D , 5D ), VS. PREORBITAL SCUTELLATE PLATE AND THE HEPATIC BOLETATE ORNAMENTATION FORM TOGETHER A VERy LARGE LEAF-LIKE PLATE WHOSE CIRCUMFERENCE IS MUCH BROADER THAN THE STEM IN Scyramathia ( FIG. 1B–D ); 3) TRANSVERSAL ROW OF STRONG, ACUTE SPINES EXTENDING SUBPARALLELy ALONG THE POSTERIOR MARGIN OF THE CARAPACE AND RUNNING ACROSS THE INTESTINAL REGION ( FIGS. 5D , 6D , 11B ), VS. TRANSVERSAL ROW OF SPINES LACKING IN Scyramathia ( FIG. 1B, C ); 4) ANTENNAL SEGMENT 2+3 WITH ONE ANTERO-VENTRO-LATERAL AND ONE POSTERO-VENTRO-LATERAL, NEARLy EQUAL IN SIZE, STRONG SPINES ( FIGS. 5C, D , 6B , 7C, D , 9B , 11B ), VS. LATERAL AND MESIAL MARGINS OF THE ANTENNAL ARTICLES 2 + 3 DISTINCTLy EXPANDED INTO LOBES, DEVOID OF SPINES IN Scyramathia ( FIG. 1D ); 5) PTERyGOSTOMIAL TEETH DISTINCT, VERy STRONG, ACUTE ( FIG. 5D , 6B ), VS. PTERyGOSTOMIAL TEETH COALESCENT AT THE BASE, RATHER INDISTINCT DISTALLy FORMING A PROMINENT PTERyGOSTOMIAL RIDGE IN Scyramathia ( FIG. 1D ); 6) FIRST AND SECOND MALE ABDOMINAL SOMITES WITH ONE STRONG, AXIAL SPINE EACH—SMALLER IN THE FEMALES ( FIG. 6D ), VS. FIRST AND SECOND MALE ABDOMINAL SOMITES DEVOID OF SPINES IN Scyramathia ( FIG. 1B ); 7) ANTEROLATERAL ANGLE OF THE BUCCAL FRAME PROTRUDED INTO A STRONG, ACUTE SPINE ( FIG. 6B ), VS. ANTEROLATERAL CORNER SHOWING AS A ROUNDED LOBE IN Scyramathia ( FIG. 1D ). Minyorhyncha n. gen. CAN BE EASILy DISTINGUISHED FROM Anamathia By THE: 1) CARAPACE DISTINCTLy SUBCIRCULAR IN OUTLINE, DORSAL SURFACE REMARKABLy GLOBOSE, PARTICULARLy SWOLLEN AT THE PROTOGASTRIC AND BRANCHIAL REGIONS, FURNISHED WITH NUMEROUS, ACUTE SPINES OF MODERATE SIZE ( FIGS. 4D , 5D , 6A , 8 , 11B , 12D ), VS. CARAPACE PEAR-SHAPED, WITH EXTREMELy LONG, ACUTE SPINES ( FIGS. 3A , 12B ); 2) ROSTRUM SHORT RELATIVE TO CARAPACE LENGTH, STRAIGHT ( FIGS. 4D , 5D , 8 , 11B ), VS. ROSTRAL SPINES EXTREMELy LONG AND REMARKABLy DIVERGENT IN Anamathia ( FIG. 3A, B, D ); 3) DORSAL MIDLINE OF THE CARAPACE WITH 6 ACUTE, MODERATE IN SIZE SPINES ( FIGS. 4C, D , 5A–D , 6A , 11B, 11D ), VS. CARAPACE WITH 3 (4 IN A. hystrix ) EXTREMELy LONG SPINES IN Anamathia (FIG. A); 4) ANTENNAL SEGMENT 2+3 WITH ONE ANTERO-VENTRO-LATERAL AND ONE POSTERO-VENTRO-LATERAL, NEARLy EQUAL IN SIZE, STRONG SPINES ( FIGS. 5C, D , 6B , 7C, D , 9B , 11B ), VS. ANTENNAL SEGMENT 2+3 WITHOUT SPINES IN Anamathia ( FIG. 3B, D ); 5) CHELIPED CARPUS DEVOID OF STRONG, ACUTE SPINES ( FIG. 8 ), VS. CHELIPED CARPUS WITH A STRONG, ACUTE SPINE IN Anamathia ( FIG. 3A ); 6) MALE CHELIPED EXTREMELy LONG, MUCH LONGER THAN P2 IN FULL GROWN SPECIMENS ( FIG. 8 ), VS. CHELIPED MUCH SHORTER THAN P2 IN Anamathia ( FIG. 3A, B ); 7) G1 KEEL ABSENT ( FIG. 13G, H ), VS. KEEL WELL DEVELOPED IN Anamathia ( FIG. 13C–F ). IT IS NOTEWORTHy THAT WHILST THE GENERA Minyorhyncha n. gen. , Anamathia AND Scyramathia PRIMARILy CONTAIN DEEP-WATER SPECIES, Rochinia gracilipes IN ACTUALLy A SHALLOW-WATER SPECIES (RANGING FROM 10 TO 175 M). Etymology. THE NAME Minyorhyncha IS A COMBINATION OF THE GREEK WORDS minys (SHORT, SMALL) AND rhynchos (NOSE, ROSTRUM) REFERRING TO THE REDUCED SIZE OF THE ROSTRUM IN FULLy DEVELOPED ADULTS. GENDER FEMININE.