Gammarus cf. subaequalis, Martynov, 1935

Sidorov, Dmitry, Hou, Zhonge & Sket, Boris, 2018, Three new remarkable amphipod species (Crustacea: Gammaridae) from springs and subterranean waters of Central Asia, Zootaxa 4444 (4), pp. 437-461 : 449-452

Gammarus cf. subaequalis -Garlyk

FIGURES 1C , 9–11

probable syn.: Rivulogammarus subaequalis Martynov 1935 , p. 440, figs 30-35 (orig. descrip.), non Gammarus

(Rivulogammarus) syriacus subaequalis: Birštejn 1948 , p. 263, fig. 1.

Material examined. TURKmEnISTAn: FOUR SPEcImEnS 16/3 - DAS: 3 mALES, 9.5 mm, 2X 11.5 mm, FEmALE, 8.5 mm, OOSTEGITES DEVELOPED, SETOSE, bEARInG 10 mEDIUm-SIZED EGGS DISSEcTED On SLIDES; SmALL STREAm WITH RIcH ImmERSED VEGETATIOn In KARAbULAK RIVER bASIn, 37.589167, 66.340833, 324 m A.S. L., nEAR GARLYK, KöýTEnDAG DISTRIcT, LEbAP PROVIncE, LEG . 25 MAY 2015 bY B. SKET.

Diagnosis. A mODERATELY STOUT Gammarus WITH SmOOTH bODY, EYES nORmAL; EPImERA DISTO-POSTERIORLY POInTED; UROSOmITES WITH PAIRED DORSAL SPInES, mEDIAn GROUPS I– II DIVIDED InTO 2 PAIRS OF SPInES EAcH; TELSOn AS WIDE AS LOnG, ITS LObES WITH 2 -3 APIcAL AnD 1 bASOFAcIAL SPInES, SETAE mODERATELY nUmEROUS On THE FAcE; bOTH AnTEnnAE WITH ScARcE AnD SHORT SETAE; GnATHOPODS RIcHLY SETOSE, ARTIcLES 4-6 OF PEREOPODS III–IV WITH DEnSE bRUSHES OF LOnG SETAE; bASIS OF PEREOPOD V DISTALLY WIDE, OF VII bROADLY ROUnDED; UROPOD III EnDOPODITE 86% OF EXOPODITE, ALL mARGInS SETOSE.

GenBank accession number: MG655630 FOR ISOLATE 516GGARLYKTUM.

Short description. GENERAL BODY MORPHOLOGY ( FIGS 1C , 11B, F, G ). Body SmOOTH. Coxae I–IV DISTALLY ROUnDED WITH OnLY FEW SHORT mARGInAL SETAE. Epimera DISTO-POSTERIORLY AcUTE, bUT nOT PRODUcED, cOXAE II–III WITH 2-3 SPInES ALOnG DISTAL mARGIn. Urosomites DORSALLY WITH SLIGHT ELEVATIOnS, SPInES AT THE POSTERIOR mARGIn, SPInES WITH SOmE SETAE mAInLY PAIRED, mEDIAn GROUPS OF I–II DIVIDED InTO TWO SEPARATE PAIRS; III WITH mEDIAn GROUP REPLAcED bY SOmE SETAE. FORmULA FOR UROSOmITES I–III IS: 3–2–2–2 // 2–2–2–2 // 2–0–3. Telson AS WIDE AS LOnG; LObES WITH 2-3 SPInES APIcALLY AnD 1 SPInE bASOFAcIALLY, WITH UP TO 15 SETAE, UP TO HALF LOnGER THAn APIcAL SPInES, GROUPED In APIcAL AnD SOmE FAcIAL GROUPS. ANTENNAE ( FIGS 1C , 9A, B ). Antenna I cA. 50% OF bODY LEnGTH, PEDUncLE ARTIcLES LEnGTHS 10:7:5, POORLY SETOSE WITH SOmE DISTAL SHORT SETAE In THE mIDDLE; FLAGELLUm OF 28, AccESSORY FLAGELLUm OF 4 ARTIcLES, FLAGELLAR SETAE UP TO HALF AS LOnG AS ARTIcLES. Antenna II 72% OF AnTEnnA I LEnGTH, LOnG ARTIcLES AnD FLAGELLUm LEnGTHS 10:9:19; FLAGELLUm WITH 15 ARTIcLES AnD WITH cALcEOLI; POORLY SETOSE, SETAE AS LOnG AS WIDTHS OF bEARInG ARTIcLES. MOUTH PARTS (TYPIcAL GAmmARID, FIGS 9C–J ). Mandibula WITH cA. 10 SETAE On PALP ARTIcLE 2; ARTIcLE 3 WITH TWIcE 3 B SETAE AnD A GROUP AT OUTER mARGIn. Maxilla I OUTER LObE WITH 11 SPInES, THE InnER HALF FInELY cOmb-SHAPED, OUTER WITH SHORTER AnD THIcKER DEnTIcLES; PALPUS ASYmmETRIc, DISTALLY WITH 5 TEETH AnD 2 SETAE, OR WITH cA. 10 DIFFEREnTLY THIcK SETAE RESPEcTIVELY. GNATHOPODS ( FIGS 10A, B ). Gnathopods SHAPED AnD SETOSE LIKE In G. parvioculatus , sp. n. PEREOPODS ( FIGS 10C–G ). Pereopods III–IV ARTIcLES 4-5 WITH DEnSE bRUSHES OF SETAE ALOnG POSTERIOR SIDES. Pereopod V bASE DISTALLY nOT mARKEDLY nARROWED, WITH A LARGE, bUT ROUnDED REcTAnGULAR DISTO-POSTERIOR LObE; AnTERIOR mARGIn WITH cA. 10 SPInES. Pereopod VII cA. 52% OF bODY LEnGTH; bASE POSTERIORLY cOnVEX, TAPERInG DISTALLY, WITH mAnY SmALL SETAE, DISTOPOSTERIOR cORnER ROUnDED. PLEOPODS AND UROPODS ( FIGS 11A, C–E ). Pleopods ORDInARY. Uropods I–II WITH 1-2 SInGLE OR PAIRED SPInES ALOnG bRAncHES, DISTAL SPInES VERY SHORT. Uropod III EnDOPODITE 86% OF EXOPODITE, ALL mARGInS DEnSELY SETOSE WITH PLUmOSE SETAE, EXcEPT bASALLY; EXOPODITE ARTIcLE 2 WELL DEVELOPED, TWIcE AS LOnG AS SURROUnDInG SPInES.

Female. BODY 8.5 mm LOnG. Antenna I WITH 24 ARTIcLES. Pereopods V TO VII WITHOUT SETAE On THE AnTERIOR mARGInS. Uropod III In ALL cHARAcTERS SImILAR AS In mALE, jUST SmALLER AnD LESS RIcHLY SETOSE.

Ecology and distribution. THIS POPULATIOn InHAbITS A SmALL EPIGEAn STREAm WITH RIcH VEGETATIOn In THE VILLAGE GARLYK, nOT cLOSE TO AnY SPRInG. A SERIES OF POPULATIOnS, VERY cLOSE TO IT mOLEcULARLY, IS DISTRIbUTED In THE LInE FROm GARLYK In TURKmEnISTAn TILL YSYK KöL ( YSSYK KUL) AREA In KYRGYZSTAn ( SKET et al. In PREP.) . THEY HAVE nOT bEEn mORPHOLOGIcALLY STUDIED. ALTHOUGH InHAbITInG THE SAmE AREA AS bOTH PREVIOUSLY DEScRIbED SPEcIES In THE EXTREmE EAST OF TURKmEnISTAn , IT IS OnLY FEEbLY RELATED TO THEm.

Remarks. Gammarus cF. subaequalis -GARLYK SEEmS TO REPRESEnT THE mOST WIDELY SPREAD EPIGEAn TAXOn OF Gammarus In CEnTRAL ASIA bETWEEn E TURKmEnISTAn AnD E KYRGYZSTAn, IT IS mORPHOLOGIcALLY SImILAR TO G. subaequalis MARTYnOV, 1935 AnD G. turanus MARTYnOV, 1935 AnD TO SOmE OTHER TAXA OF MARTYnOV (1935) AS WELL AS TO Gammarus lacustris G.O. SARS, 1863. Gammarus turanus IT RESEmbLES PARTIcULARLY In THE SHAPE OF PEREOPOD V bASE, bUT IT IS VERY DIFFEREnT In TELSOn SHAPE AnD SETATIOn. In TELSOn AnD In UROPOD III DImEnSIOnS AnD SETATIOn, IT IS cLOSER TO G. subaequalis . OUR TAXOn IS VERY DIFFEREnT FROm bOTH In UROSOmAL SPInES. Gammarus lacustris DIFFERS mAInLY In mORE AcUTE EPImERA. THEY ALSO RESEmbLE TO SOmE DEGREE Gammarus pseudosyriacus KARAmAn ET PInKSTER, 1977 In WHIcH, HOWEVER, THE UROPOD III EnDOPODITE IS SHORTER AnD UROSOmE cARInATIOn IS mUcH STROnGER. In THE PHYLOGRAm OF THE AGGREGATE lacustris (SKET et al. In PREP.) THE EnTIRE GROUP OF POPULATIOnS IS POSITIOnED In THE TERmInAL SUbcLADE lacustris-A WHIcH cOnTAInS mAInLY ASIATIc POPULATIOnS OF THE G. lacustris SHAPE, bUT ALSO THE AbERRAnT Gammarus bergi KARAmAn ET PInKSTER, 1977 AnD SOmE NORTH AmERIcAn G. cF. lacustris POPULATIOnS. THE TYPE LOcALITY OF THE MARTYnOV'S G. subaequalis IS A SPRInG In GALKInO nEAR SHImKEnT, 150 Km NE TASHKEnT; G. turanus AT THE SPA In CHImGAn. BOTH LOcALITIES ARE LESS THAn 100 Km APART AnD 400 TO 500 Km NE FROm GARLYK, bUT OnLY cA. 200 Km AWAY FROm THE LInE GARLYK—YSYK KöL, WHIcH IS SPARSELY InHAbITED bY POPULATIOnS OF Gammarus cF. subaequalis -GARLYK.

Figures

FIGURE 1. Habitus of examined specimens: (А) Gammarus troglomorphus, sp. n.; (B) Gammarus parvioculatus, sp. n.; (C) Gammarus cf. subaequalis-Garlyk; (D) Tadzocrangonyx alaicus, sp. n.

FIGURE 9. Gammarus cf. subaequalis-Garlyk, male, 11.5 mm, 16/3-DАS: (А) antenna I; (B) antenna II; (C) mandible, left; (D) mandible, right; (E) maxilla I, right; (F) palp of maxilla I, left; (G) maxilla II; (H) upper lip; (I) lower lip; (J) maxilliped. Scale bars 0.2 mm.

FIGURE 10. Gammarus cf. subaequalis-Garlyk, male, 11.5 mm, 16/3-DАS: (А) gnathopod I; (B) gnathopod II; (C) pereopod III; (D) pereopod IV; (E) pereopod V; (F) pereopod VI; (G) pereopod VII. Scale bars 0.2 mm.

FIGURE 11. Gammarus cf. subaequalis-Garlyk, male, 11.5 mm, 16/3-DАS: (А) pleopod I; (B) epimeral plates; (C) uropod I; (D) uropod II; (E) uropod III; (F) telson; (G) urosoma, dorsal view. Scale bars 0.2 mm.