Bioacoustics of Anaxyrus williamsi

Distribution. Bufo ( Anaxyrus ) williamsi IS fOUND ONLY WITHIN WETLANDS Of LIMITED EXTENT fED fROM ARTESIAN SPRINGS ON THE WESTERN EDGE Of THE DIXIE VALLEY PLAYA, EAST Of THE STILLWATER RANGE IN DIXIE VALLEY, NV ( FIG. 2b ). VERY ISOLATED AND RESTRIcTED IN SIZE, THE ENTIRE ESTIMATED GEOGRAPHIc RANGE IS APPROXIMATELY 6 kM2, WITH NO USAbLE cORRIDORS TO OTHER TOAD HAbITAT OUTSIDE DIXIE VALLEY. FOUR SPRING DIScHARGE SITES AND THE MARSH HAbITAT DOWNSTREAM Of THE SPRINGS ARE SEPARATED fROM EAcH OTHER AND INTERRUPTED bY SAGEbRUSH STEPPE DOMINATED bY bIG SAGEbRUSH ( Artemisia tridentata SSP. tridentata ), GREASEWOOD ( Sarcobatus vermiculatus ), RUbbER RAbbITbRUSH ( Ericameria nauseosa ) AND SALTbUSH ( Atriplex SPP.) ( BLM 2011 ). THE SPRING-fED WETLANDS SUPPORT MARSH VEGETATION SUcH AS SPIkERUSH ( Eleocharis SPP.), kNOTWEED ( Polygonum SPP.), cANARYGRASS ( Phalaris SPP.), DUckWEED ( Lemna SP.), VARIOUS SPEcIES Of RUSH ( Juncus SP.), cOMMON REED ( Phragmites australis ), AND cATTAIL ( Typha SPP.) ( BLM 2011 ), AND TOADS ARE TYPIcALLY fOUND IN SHALLOW WATER OR ASSOcIATED WITH MOIST SOILS WITHIN THE IMMEDIATE PERIMETER Of THE RIPARIAN AREAS THAT bORDER SAGEbRUSH HAbITAT. Natural history. Bufo ( Anaxyrus ) williamsi IS RESTRIcTED TO THE SPRING fED-WETLAND HAbITAT ALONG THE WESTERN EDGE Of THE DIXIE VALLEY PLAYA. SIMILAR TO OTHER TOADS IN THE B. boreas cOMPLEX (EXcEPT PERHAPS B. exsul , WHIcH IS MORE AQUATIc), THE TERRESTRIAL B. williamsi IS TYPIcALLY NOcTURNAL, EMERGING AT DUSk, AND cAN bE fOUND IN MOIST VEGETATION OR IN VERY STILL, SHALLOW WATER WITH VERY LITTLE VEGETATION cANOPY. DIXIE VALLEY EXPERIENcES EXTREME TEMPERATURE fLUcTUATIONS bETWEEN DAY AND NIGHT TEMPERATURES, AS WELL AS SEASON-TO-SEASON EXTREMES, cHARAcTERISTIc Of cOLD DESERT EcOSYSTEMS. IN AUTUMN, IT IS LIkELY THAT B. williamsi RETREATS TO bURROWS TO HIbERNATE, EMERGING IN SPRING TO bREED. BREEDING OccURS fROM MARcH TO JUNE (FORREST et al . 2013). SEXUALLY MATURE MALES cONGREGATE IN SHALLOW WATER AROUND THE PERIMETER Of WETLAND VEGETATION. Bufo ( Anaxyrus ) williamsi DOES NOT HAVE AN ADVERTISEMENT VOcALIZATION, bUT RETAINS A RELEASE cALL USED bY MALES WHEN IN cONTAcT WITH OTHER MALES. EGG MASSES AND TADPOLES DEVELOP IN STILL, SHALLOW WATER WITHIN THE MARGINS Of THE MARSH HAbITAT, WHERE THERE ARE ADEQUATE TEMPERATURES fOR DEVELOPMENT AS IS SEEN WITHIN B. boreas ( KARLSTROM 1962 ; CAREY et al . 2005) . TOADLETS ARE GENERALLY fULLY METAMORPHOSED IN APPROXIMATELY 10 WEEkS (FORREST et al . 2013). WHILE B. williamsi IS REPORTEDLY AcTIVE THROUGHOUT THE SUMMER (KRIS URQUHART, PERS. cOMM.), LITTLE IS kNOWN REGARDING DISPERSAL AND NON-bREEDING bEHAVIOR Of THIS TOAD. THE OVERALL POPULATION NUMbERS Of THIS TOAD ARE UNkNOWN; HOWEVER, THE cURRENT RANGE IS SEVERELY RESTRIcTED, SUGGESTING THAT THIS SPEcIES’ POPULATION IS LIkELY VERY SMALL.

Diagnosis. Bufo ( Anaxyrus ) williamsi IS DISTINGUISHAbLE fROM B. boreas bY A cOMbINATION Of DIAGNOSTIc MORPHOLOGIcAL cHARAcTERS ( FIG. 4 ; TAbLE 1 , TAbLE 2 ), GENETIc EVIDENcE ( FIG.3 , FIG. 6 ), AND LOcALIZED DISTRIbUTION ( FIG. 2b ). Bufo ( Anaxyrus ) williamsi IS DISTINcT fROM B. boreas bY: A SMALL ADULT bODY SIZE (SVL IS MORE THAN 2.5 cM SMALLER THAN B. boreas ; TAbLE 1 ); SIGNIfIcANTLY, bUT MODESTLY, LARGER, cLOSELY-SET EYES, AND SMALLER HEAD ( TAbLE 2 ); STATISTIcALLY AND PERcEPTIbLY LARGER TYMPANUM, AND SHORTER HIND LIMbS; cONSPIcUOUSLY LARGE AND ELEVATED TIbIAL GLANDS; AND DISTINcTIVE cOLOR PATTERN ( FIG. 4A , FIG. 4b ). smaller or larger (↑) states exhibited by congeneric species when compared to B. williamsi . B. williamsi (n=30) B. exsul (n=30) B. nelsoni (n=31) B. boreas (n=289) SVL 56.3 64.0 ↑ 80.8 ↑ 82.3 ↑ CI 52.1, 60.4 59.8, 68.1 76.8, 84.9 81.0, 83.7 HL 22.2 22.0 23.4 ↑ 23.1 ↑ CI 21.7, 22.6 21.5, 22.4 23.0, 23.8 23.0, 23.3 HW 25.2 25.0 27.4 ↑ 26.5 ↑ ......continued on the next page B. williamsi (n=30) B. exsul (n=30) B. nelsoni (n=31) B. boreas (n=289) CI SL 24.6, 25.8 5.62 24.5, 25.6 5.10↓ 27.0, 27.9 5.31 26.4, 26.7 5.40 CI 5.43, 5.83 4.91, 5.30 5.14, 5.50 5.34, 5.46 IND 4.87 4.81 5.15 4.84 CI ED 4.68, 5.05 7.83 4.64, 4.99 6.98 ↓ 4.99, 5.31 7.45 4.79, 4.90 7.24 ↓ CI 7.58, 8.01 6.77, 7.19 7.26, 7.65 7.18, 7.31 IOD 11.8 11.4 11.9 12.5 ↑ CI TYM 11.5, 12.2 4.46 11.07, 11.77 4.06 ↓ 11.58, 12.22 4.06 ↓ 12.40, 12.62 4.10 ↓ CI 4.28, 4.65 3.88, 4.23 3.89, 4.22 4.04, 4.15 PTW 6.65 6.32 6.75 6.87 CI 6.33, 6.97 6.02, 6.62 6.47, 7.02 6.78, 6.96 PTL 8.57 8.04 8.65 9.69 ↑ CI 8.12, 9.02 7.62, 8.46 8.26, 9.05 9.55, 9.82 IPD 14.9 14.4 15.2 15.2 CI 14.5, 15.4 14.0, 14.9 14.8, 15.6 15.1, 15.3 FML 29.5 29.3 30.4 31.6 ↑ CI 28.8, 30.2 28.6, 30.0 29.8, 31.0 31.4, 31.8 TBL 28.3 29.1 29.6 ↑ 31.0 ↑ CI 27.6, 29.0 28.5, 29.8 29.0, 30.2 30.8, 31.2 FTL 29.9 30.8 31.9 ↑ 32.7 ↑ CI 28.9, 30.8 30.0, 31.7 31.1, 32.7 32.4, 32.9 Bufo ( Anaxyrus ) williamsi IS THE SMALLEST bUfONID WITHIN THE B . boreas SPEcIES cOMPLEX ( TAbLE 1 , TAbLE 2 ). THIS NEW SPEcIES HAS A STATISTIcALLY, bUT MODESTLY SHORT, NARROW HEAD SIMILAR TO THE SMALL SIZED B. exsul , bUT B. williamsi cAN bE DISTINGUISHED fROM B. exsul bY A SIGNIfIcANTLY, bUT MODESTLY, LONGER RELATIVE SNOUT LENGTH cOMPARAbLE TO THAT B. boreas AND B. nelsoni ( TAbLE 2 ). Bufo ( Anaxyrus ) williamsi HAS RELATIVELY LARGE, cLOSELY SET EYES AND PERcEPTIVELY LARGE TYMPANUM, WHIcH DISTINGUISHES THIS TOAD fROM ALL TAXA WITHIN THE B. boreas SPEcIES cOMPLEX. THE PAROTOID GLANDS ARE SLIGHTLY LONGER THAN WIDE, bUT ARE cOMPARATIVELY SHORTER OVERALL THAN PAROTOIDS Of B. boreas ( TAbLE 2 ). Bufo ( Anaxyrus ) williamsi HAS HIND LEGS THAT ARE SIMILAR IN RELATIVE SIZE TO B. exsul , bUT SIGNIfIcANTLY AND PERcEPTIbLY SHORTER THAN THOSE Of B. boreas AND B. nelsoni . THE TIbIAL GLANDS EXHIbITED IN B. williamsi ARE cONSPIcUOUS AND APPROXIMATELY THE WIDTH Of THE PAROTOID GLANDS, REGULAR IN SHAPE AND RUST cOLORED WITH LITTLE VARIATION AMONG INDIVIDUALS Of THIS SPEcIES. IN ADDITION TO MORPHOLOGIcAL SHAPE DIffERENcES, B. williamsi EXHIbITS UNIQUE cOLORATION DIffERENT fROM TAXA Of THE B. boreas SPEcIES cOMPLEX. THE DORSAL GROUND cOLOR cONSISTS Of OLIVE SHADES THAT cONTAIN MINUTE bLAck fLEckS, RUST cOLORED WARTS ARE bORDERED bY fINE, bLAck HALOS, AND PROMINENT PAROTOID GLANDS ARE PALE TAN AND bLAck SPEckED. THE VENTER Of B. williamsi IS SIMILAR TO B. exsul , EXHIbITING SHARPLY cONTRASTED bLAck MARbLING AGAINST A WHITE bAckGROUND cOLOR ON THE ANTERIOR SIDES Of THE LIMbS AND bELLY. THE PRESENcE Of A DORSAL STRIPE IS VARIAbLE AMONG INDIVIDUALS Of B. williamsi , AS IS SIMILAR TO THE OTHER MEMbERS Of THE B . boreas cOMPLEX, WITH THE EXcEPTION Of B. exsul . DISTINcT NUPTIAL PADS DEVELOP ON THE DORSAL SIDE Of THE THUMb IN MALES Of B. williamsi , A TYPIcAL SEcONDARY SEXUAL cHARAcTERISTIc EXHIbITED AMONG MOST bUfONIDS. THIS SPEcIES LAckS AN ADVERTISEMENT cALL, bUT RETAINS A RELEASE cALL THAT SOUNDS LIkE THE WEEPING Of A cHIck ( STEbbINS 2003 ). THE cALL IS EMITTED WHEN MALES cOME INTO cONTAcT WITH ONE ANOTHER, SIMILAR TO cONGENERS Of THE B. boreas cOMPLEX.