Cladocera from the Upper Xingu River Basin with the description of a new genus of the Chydoridae (Crustacea: Branchiopoda: Anomopoda) Author Sousa, Francisco Diogo R. Author Elmoor-Loureiro, Lourdes M. A. text Zootaxa 2018 4418 6 545 561 journal article 30092 10.11646/zootaxa.4418.6.3 a6f0a2ca-a13e-4525-898c-a37de2665345 1175-5326 1245400 B390C24F-F8B9-4B7B-9930-B98D56FBA082 Kisakiellus aweti gen.nov., sp. nov. ( FIgS 2–6 ) Etymology. AWETI IS A SMALL INDIgENOUS ETHNICITY THAT INHAbITS A TERRITORY NEAR THE TYPE LOCALITY. Type locality. A fIRST ORDER STREAM LOCATED IN UPPER XINgU RIVER BASIN , MATO GROSSO , BRAZIL ( 12°50'9.89"S , 52°20'0.30"W ). Type material. Holotype . UNDISSECTED ADULT PARTHENOgENETIC fEMALE IN A TUbE WITH 92 % ETHANOL DEPOSITED AT THE MUSEUM Of ZOOLOgY Of THE UNIVERSITY Of SãO PAULO UNDER ACCESS NUMbER MZUSP36692 . THE LAbEL Of THE HOLOTYPE IS: “ Kisakiellus aweti , 1 PARTH . ♀ fROM A fIRST ORDER STREAM IN UPPER XINgU RIVER BASIN , MATO GROSSO , BRAZIL , HOLOTYPE ” . Paratypes . TWO ADULT PARTHENOgENETIC fEMALES fROM A fIRST ORDER STREAM IN UPPER XINgU RIVER BASIN , MATO GROSSO ( 12°50'9.89"S , 52°20'0.30"W ), MATERIAL COLLECTED ON 10/08/2017 bY TIAgO BORgES KISAKA ( FDRS 0522). THREE ADULT PARTHENOgENETIC fEMALES fROM A fIRST ORDER STREAM IN UPPER XINgU RIVER BASIN , MATO GROSSO ( 13°5'58.40"S , 52°21'57.52"W ), MATERIAL COLLECTED ON 08/08/2017 bY TIAgO BORgES KISAKA ( FDRS 0523). Diagnosis. SAME AS fOR THE gENUS. Description. Parthenogenetic females. General Habitus ( FIg. 2A–F ). BODY ELONgATED IN LATERAL VIEW, 0.50– 0.55 MM LENgTH, RELATIVELY LOW; HEIgHT/LENgTH RATIO IS APPROXIMATELY 0.4; WITHOUT A DORSAL KEEL; DORSAL MARgIN WITH A SHALLOW DEPRESSION bETWEEN THE ARTICULATION Of VALVE AND THE HEAD SHIED, SLIgHTLY CONCAVE NEAR THE POSTERODORSAL CORNER; VENTRAL MARgIN WITH WIDE ANTERIOR fLANgES. IN DORSAL AND VENTRAL VIEWS, THE bODY IS bROAD OVAL; VENTRAL VIEW MARKED bY TWO MARgINAL LINES, THE INNERMOST PEAR-SHAPED, CORRESPONDINg TO THE VENTRAL MARgIN WHICH bEARS TWO ANTERIOR WIDE fLANgES AND SETAE. OUTERMOST MARgINAL LINE CORRESPONDS TO A fLAP WHICH SURROUNDS THE ENTIRE VALVES; A SHALLOW gROOVE IS PRESENT bETWEEN THE INNERMOST AND OUTERMOST MARgINAL LINES; IN fRONTAL AND POSTERIOR VIEWS THE bODY IS bELL-SHAPED, bILObED. Carapace ( FIg. 2A–H ). DIVIDED bY A RELATIVELY DEEP MID-DORSAL DEPRESSION; EACH LObE IS MARKED WITH SEVERAL NARROW AND SHALLOW gROOVES; ANTEROVENTRAL MARgINS WITH WIDENED fLANgES ARMED WITH A fRINgE Of PLUMOSE SETAE WHICH COVERS THE fLANgES THEMSELVES. VENTRAL MARgIN ARMED WITH SEVERAL INTERNALLY ARTICULATED PLUMOSE SETAE, SETAE INSERTED ON THE VENTRAL PART Of THE POSTERIOR MARgIN ORIENTED TOWARDS THE INTERIOR Of THE fILTER CHAMbER. POSTERIOR MARgIN STRONgLY CONCAVE, NAKED, WITH A SHORT AND ObTUSE PROjECTION; MARgIN Of THE fLAP NAKED, WITH A THICK bORDER. Cephalic structures ( FIg. 3A–F ). Ocellus SHORTER THAN THE EYE (2A,C,E). Rostrum VERY WIDE, UNIfORMLY CURVED AND WITH A THICK bORDER ( FIg. 2B–D ). Head shield ( FIg. 3A–B ). CENTRAL PART MARKED WITH SEVERAL NARROW AND SHALLOW gROOVES, LATERAL PARTS EXPANDED fROM THE MANDIbULAR ARTICULATION; fORNICES WITH APEX SHARP WHICH ARE POSITIONED AbOVE THE fLAP Of THE VALVES; TWO MAIN HEAD PORES NOT CONNECTED; PP/IP AbOUT 1; DIAMETER Of ANTERIOR PORE SHORTER THAN POSTERIOR ONE; SECONDARY HEAD PORES AbSENT. Labrum ( FIg. 3C ). KEEL NOT PROMINENT, ELONgATED; APEX ARMED WITH LONg SETULAE; ANTERIOR MARgIN WITH A DEPRESSION NEAR THE APEX; LATERAL HORNS PRESENT. Maxilla ( FIg. 3D ). WELL DEVELOPED, WITH TWO LONg SETULATED SETAE. Antennule ( FIg. 3E ). ANTENNULAR bODY ARMED WITH fOUR ROWS Of SHORT SETULAE; DISTAL PART DILATED; LENgTH Of AbOUT 2.1 TIMES THE WIDTH, EXCEEDINg THE MARgIN Of THE ROSTRUM; ANTENNULAR SENSORY SETA THICK, CURVED, AbOUT 1.2 TIMES SHORTER THAN THE LENgTH Of THE ANTENNULAR bODY, INSERTED LATERALLY TO THE APICAL AESTHETASCS; NINE AESTHETASCS NEVER EXCEEDINg THE LENgTH Of THE ANTENNULAR bODY. Antenna ( FIg. 3F–G ). COXAL SETAE AbOUT TWO TIMES SHORTER THAN THE fIRST EXOPODITE SEgMENT; ANTENNAL fORMULA (EXO/ENDO): SPINES 001/101, SETAE 013/003; bASAL SEgMENT THICK AND WITH A SHORT THIN SPINE; fIRST EXOPODITE AND ENDOPODITE SEgMENTS Of DIffERENT LENgTH. FIRST ENDOPODITE SEgMENT ARMED WITH A SHORT AND THIN SPINE AbOUT 0.6 Of THE LENgTH Of THE APICAL SPINE; APICAL SPINES Of SIMILAR LENgTH; SETA ON THE SECOND EXOPODITE SEgMENT VERY LONg, SIMILAR IN LENgTH TO THE LONgEST APICAL SETAE. FIVE PAIRS Of THORACIC LIMbS. Limb I ( FIg 4A–D ). EPIPODITE AND gNATHObASE NOT STUDIED. ODL bEARS A SHORT AND CHITHINIZED SETA ARMED WITH THIN SPINES, SLIgHTLY LONgER THAN THE IDL fIRST SETA. IDL (EN4) WITH THREE SETAE; THIRD SETA AbOUT TWO TIMES LONgER THAN SECOND SETA, CHITHINIZED, DENSELY SETULATED, fEATHER-LIKE; SECOND SETA AbOUT 1.4 TIMES LONgER THAN fIRST SETA, CHITHINIZED, ARMED WITH SHORT SPINES DECREASINg IN LENgTH TOWARDS TO DISTAL PART; fIRST SETA SHORT, CHITHINIZED, WITH CURVED APEX, ARMED WITH THIN SPINES. ENDITE 3 WITH TWO POSTERIOR PLUMOSE SETAE Of SIMILAR LENgTH (A–b) AND A LARgE gLObULAR ELEMENT. ENDITE 2 WITH THREE PLUMOSE POSTERIOR SETAE (C–E); SETA (C) SHORTER THAN SETAE (D–E); STIff SETA SETULATED fROM THE MEDIAN PART ONWARDS. ENDITE 1 WITH THREE POSTERIOR bISEgMENTED, DENSELY SETULATED SETAE (f–H) Of SIMILAR LENgTH, STIff SETA SETULATED fROM THE MEDIAN PART ONWARDS; EjECTOR HOOKS Of DIffERENT LENgTHS, ARMED WITH HARD SETULAE; VENTRAL fACE Of THE LIMb WITH SEVERAL LONg SETULAE NOT ORgANIZED IN CLUSTERS. Limb II ( FIg. 4E ). EXOPODITE MARKEDLY SHORT, TRIANgULAR SHAPED, WITHOUT SETA; INNER LIMb PORTION ARMED WITH EIgHT SETAE, Of WHICH fIVE ARE SCRAPERS (1–5) AND THREE ARE PLUMOSE (6–8). THIRD SCRAPER TICK, MARKEDLY LONgER THAN THE OTHERS; fIfTH SCRAPER TICKER AND SHORTER THAN THE fOURTH SCRAPER, ARMED WITH SPINES; SCRAPERS 1–4 ARMED WITH HARD SETULAE. EIgHTH SETA TICK, PLUMOSE, AbOUT 1.8 TIMES LONgER THAN THE SIXTH AND SEVENTH SETAE; PROXIMAL PORTION Of THE gNATHObASE NOT ELONgATED AND ARMED WITH LONg SETULAE; DISTAL PORTION ARMED WITH fOUR ELEMENTS AND A DENSELY SETULATED SETA. FIRST ELEMENT IS AN ELONgATED SENSILLUM; SECOND ELEMENT ELONgATED WITH A SHARP AND SETULATED DISTAL PORTION; THIRD ELEMENT ARMED WITH A gENICULATED APEX; fOURTH ELEMENT ELONgATED WITH A LATERAL PROjECTION, NAKED. FILTER COMb WITH SEVEN SETULATED SETAE; fIRST SETA DENSELY SETULATED AND SHORTER THAN THE OTHERS. Limb III ( FIg. 4A–D ). EPIPODITE NOT STUDIED. EXOPODITE WITH fOUR DISTAL AND THREE LATERAL SETAE; SETAE 3–7 SETULATED; SEVENTH SETA LONgER THAN THE SIXTH AND fIfTH SETAE; SIXTH AND fIfTH SETAE SIMILAR IN LENgTH; fOURTH SETA AbOUT 1.5 TIMES LONgER THAN THE THIRD SETA; THIRD SETA AbOUT 1.2 TIMES LONgER THAN THE SECOND AND fIRST SETAE; SECOND SETA SLIgHTLY LONgER THAN fIRST SETA. DISTAL ENDITE WITH TWO SETAE (1–2) AND AN ELEMENT bETWEEN THEM; SETA 1 MARKEDLY CHITHINIZED, SHORTER THAN SETA 2; SIX LONg AND SETULATED POSTERIOR SETAE INCREASINg IN LENgTH TOWARDS THE gNATHObASE (A–f). BASAL ENDITE WITH fOUR SETAE (3–6) AND AN ELEMENT; DISTALMOST SETA LONgER THAN THE OTHERS; gNATHObASE ARMED WITH A LONg AND CYLINDRICAL SENSILLUM AND A SETULATED PROXIMAL SETA; fILTER COMb WITH SEVEN SETULATED SETAE. Limb IV ( FIg. 4E–H ). PRE-EPIPODITE DENSELY SETULATED; EPIPODITE OVAL WITH A VERY SHORT PROjECTION; EXOPODITE HEIgHT SIMILAR TO ITS WIDTH, WITH SEVEN PLUMOSE MARgINAL SETAE. SEVENTH SETA fLAT WITH ITS DISTAL PORTION SPEARHEAD- SHAPED AND LONgER THAN THE fIRST AND SECOND SETAE. SIXTH SETA SLIgHTLY LONgER THAN THE fIfTH SETA. FOURTH AND THIRD SETAE Of SIMILAR LENgTH, AbOUT 1.6 TIMES LONgER THAN THE fIRST AND SECOND SETAE. DISTAL ENDITE WITH AN ELEMENT AND fOUR SETAE (1–4), ONE CHITHINIZED (1), THREE fLAMINg-TORCH-LIKE AND SLIgHTLY SETULATED (3–4), Of WHICH THE fIRST IS SHORTER THAN SETA 1. BASAL ENDITE ARMED WITH THREE SETULATED SETAE; gNATHObASE THICK, WITH THREE ELEMENTS, ARMED WITH A SETULATED SETA; fILTER COMb WITH SIX SETAE. Limb V ( FIg. 4I –J ). PRE-EPIPODITE DENSELY SETULATED; EPIPODITE OVAL WITH A VERY SHORT PROjECTION; EXOPODITE WIDE, qUADRANgULAR, ARMED WITH SEVERAL bUNCHES Of SETULAE; fOUR PLUMOSE SETAE. FIRST SETA POSTERIORLY INSERTED, AbOUT 1.6 TIMES LONgER THAN THE SECOND SETA. THIRD SETA SHORTER THAN fOURTH SETA; INTERNAL LObE gLObULAR, WITH A NOTCH AND ARMED WITH MANY SETULAE. TWO SETAE Of DIffERENT LENgTHS ON INNER fACE Of THE LObE, SETA 1 DENSELY SETULATED; SETA 2 WITH A CHITHINIZED APEX AND ARMED WITH STIff SPINULAE, WITH AbOUT 0.65 Of THE LENgTH Of SETA 1; gNATHObASE WITH AN ELEMENT; fILTER COMb WITH fOUR SETAE LONgER THAN THE SETAE ON THE INTERNAL LObE. Abdomen ( FIg. 2A ). WITH THREE ROWS Of SETULAE. Postabdomen ( FIg. 6A–C ). RELATIVELY SHORT , AbOUT 2.7 TIMES AS LONg AS IT IS WIDE ; WHEN IN DORSAL VIEW, DOES NOT APPEAR LATERALLY COMPRESSED. VENTRAL MARgIN STRONgLY ARCHED; PREANAL MARgIN AbOUT 1.5 TIMES LONgER THAN THE ANAL MARgIN; PREANAL AND POSTANAL ANgLES PRONOUNCED; ANAL MARgIN SLIgHTLY CONCAVE, LONgER THAN THE POSTANAL MARgIN, ARMED WITH SETULAE; POSTANAL MARgIN SLIgHTLY CONVEX AND ARMED WITH SETULAE; TWO LATERAL fASCICLES. FIGURE 2. Kisakiellus aweti gen. nov ., sp. nov . A, Habitus from adult parthenogenetic female, lateral view. B, idem , outline of body. C, idem , dorsal view. D, idem , ventral view. E, idem , frontal view. F, idem , posterior view. G, Setae on the innermost ventral margin. H, projection of the posteroventral corner of the carapace. Scale bars = 50 µm. FIGURE 3. Kisakiellus aweti gen. nov ., sp. nov . A, head shield. B, head pores. C, labrum. D, first maxilla. E, antennule. F, antenna. G, idem , setae on the second segment of the exopodite. Scale bars = 50 µm. FIGURE 4. Kisakiellus aweti gen. nov ., sp. nov . A, first limb. B, idem , endites. C, idem , ODL and IDL. D, idem , ODL seta. E, second limb. Scale bars = 50 µm. FIGURE 5. Kisakiellus aweti gen. nov ., sp. nov . A–D, third limb. A, exopodite. B, endite. C, setae and a sesillum on the distal endite. D, setae on the basal endite. E–H, fourth limb. E, exopodite. F, distal endite. G, sensillum. H, basal endite. Scale bars = 50 µm. FIGURE 6. Kisakiellus aweti gen. nov ., sp. nov . A–C, postbdomen. A, lateral view. B, dorsal view. C, postabdominal seta. D– E. hypothetical representation of the functional morphology and positive rheotactic behavior. D, arrow indicate the proposed dynamics of water flow in a lateral view. E, arrows indicate the proposed dynamics of water flow in a dorsal view. Scale bars = 50 µm. Postabdominal claw ( FIg. 6A, C ). CURVED, LONgER THAN THE ANAL AND POSTANAL MARgINS; VENTRAL MARgIN COVERED bY SPINES; DORSAL MARgIN bEARS SEVERAL SPINES, bUT THE bASE IS NAKED; bASAL SPINES AbSENT. Ephippial females and males. UNKNOWN. Differential diagnosis. SAME AS fOR THE gENUS. Distribution and Biology. SO fAR, Kisakiellus aweti gen. nov ., sp. nov . WAS ONLY ObSERVED IN THE LOCALITIES INDICATED IN TAbLES 1 AND 2 . IT IS POSSIbLE THAT POPULATIONS Of THIS TAXON OCCUR IN OTHER REgIONS Of BRAZIL , bUT THEY DON’T SEEM TO bE ASSOCIATED WITH ANY SPECIfIC SUbSTRATE. THUS, Kisakiellus aweti gen. nov ., sp. nov . CAN bE CONSIDERED A RARE SPECIES ( TAbLE 1 ). THE HEADSTREAMS SAMPLED EXHIbITED AN AVERAgE TEMPERATURE Of 21.8 °C, SLIgHTLY ACID PH (bETWEEN 4.8–5.07), LOW ELECTRIC CONDUCTIVITY (bETWEEN 5.3–6.4 µS/CM -1) AND DISSOLVED OXYgEN LEVELS bETWEEN 4.88–6.08 Mg/L. TO MORE INfORMATION, SEE THE PROjECT “CLADOCERANS fROM BRAZIL : FAMILIES CHYDORIDAE AND EURYCERCIDAE ”.