Gammarus troglomorphus, Sidorov & Hou & Sket, 2018

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 : 438-445

Gammarus troglomorphus , sp. n.

FIGURES 1A , 2–5

Material examined. HOLOTYPE SPEcImEn NC181: mALE, 12.4 mm; cOLLAPSE SInKHOLE (SInK-LAKE) SUUV OYUK, 37.596778, 66.405500, 360 m A.S. L., nEAR GARLYK (KARLjUK), KöýTEnDAG DISTRIcT, LEbAP PROVIncE, TURKmEnISTAn, LEG. 29 MAY 2015 bY B . SKET, M. PERELADOV AnD B. ZImmERmAn. PARATYPE NC182: FEmALE, 11.5 mm, OOSTEGITES DEVELOPED, SETOSE, bEARInG 19 mEDIUm-SIZED EGGS; SAmE DATA AS HOLOTYPE .

Diagnosis. A mEDIUm SIZED, PIGmEnTLESS AnD EYELESS Gammarus WITH cOnSPIcUOUSLY ELOnGATED APPEnDAGES; EPImERA EXPAnDED AcUTE, II SIcKLE SHAPED; UROSOmITES WITH DORSAL LATERALLY cOmPRESSED bULGES; PEREOPOD VII AnD UROPOD I REAcHInG cLOSE TO TIPS OF UROPOD III; SPInES OF mAXILLA I OUTER LObE DEnSELY SERRATED; UROPOD I–II RAmI SmOOTH; UROPOD III, EnDOPODITE LITTLE SHORTER THAn EXOPODITE, ALL mARGInS DEnSELY SETOSE.

GenBank accession number: MG655628 FOR ISOLATE 513GTROGLOmTUM.

Etymology. SPEcIFIc EPITHET ' troglomorphus ' REFERS TO THE ADAPTIVE cAVERnIcOLOUS mORPHOLOGIcAL FEATURES.

Description. GENERAL BODY MORPHOLOGY ( FIGS 1A , 3F, G , 4I ). A STOUT, WEAKLY SETOSE Gammarus WITHOUT DARK bODY AnD EYE PIGmEnTATIOn. Body LEnGTH UP TO 12.4 mm. Head WITH SHORT AnD ROUnDED, UP-DOWn SYmmETRIc GEnAL PLATES. Pereon AnD pleon nOT ARmED, WITHOUT DORSAL SETAE. Coxal plates I–IV WITH ROUnDED DISTAL mARGInS, WITH 2-4 SETAE EAcH, cOXAE II–III TAPERInG DISTALLY, IV LObATE. Branchia II WIDE, III–IV nARROWER, ALL LARGER THAn cOXAL PLATES. Epimeron I DISTO-POSTERIORLY OnLY SLIGHTLY PRODUcED, WITHOUT SPInES OR SETAE. Epimeron II DISTO- POSTERIORLY VERY STROnGLY PRODUcED, THE EnTIRE PLATE nEARLY SIcKLE SHAPED; WITH 2 WEAKLY DEVELOPED SPInES DISTO- AnTERIORLY AnD 2 SmALL SETAE ALOnG POSTERIOR mARGIn. Epimeron III STROnGLY PRODUcED, bUT LESS THAn EPImEROn II; OnLY WITH 2 SmALL SPInES On ITS DISTAL mARGIn. Urosomites WITH LATERALLY cOmPRESSED mEDIO-DORSAL ELEVATIOnS, WITH GROUPS OF (1-) 2 SPInES AnD (0-) 1 SETA; mEDIAn GROUPS On TOP OF ELEVATIOnS AnD WITHDRAWn AnTERIORLY; SPInES FORmULA I–III IS: 2–2–2 // 1–2–1 // 2–2–2. Telson nARROW, ITS WIDTH 75% OF LEnGTH; SPLIT TO 80% OR DEEPER; LObES APIcALLY WITH 2-3 SPInES AnD 3 LOnG SETAE, LATERALLY SInGLE GROUPS OF 2 SETAE. ANTENNAE ( FIGS 1A , 2A, B ). Antenna I 75% OF bODY LEnGTH, PEDUncLE ARTIcLES In RELATIOn 10:8:5, FLAGELLUm OF 33 ARTIcLES, WHIcH ARE APPROXImATELY TWIcE AS LOnG AS WIDE; AccESSORY FLAGELLUm OF 2 LOnG ARTIcLES. PEDUncLE ARTIcLES WITH SETAE OnLY APIcALLY, THEY ARE LESS THAn 10 AnD VERY SHORT AnD FInE; SUcH IS ALSO THE SETATIOn OF FLAGELLAR ARTIcLES, EAcH FLAGELLAR ARTIcLE bEARInG AESTHETASc, SHORTER THAn SETAE. Antenna II 45% OF AnTEnnA I LEnGTH, ITS LOnG PEDUncLE ARTIcLES AnD FLAGELLUm In RELATIOn 10:11:19; ARTIcLES 4-5 WITH LESS THAn 10 GROUPS OF 2-6 SmALL SETAE (In EAcH GROUP) ALOnG THEIR EnTIRE LEnGTHS; FLAGELLUm mODESTLY EqUIPPED WITH SHORT SETAE; nO cALcEOLI. MOUTH PARTS (TYPIcAL GAmmARID, FIGS 2C–J ). Mandibular palp WITH ARTIcLE 2 THE LOnGEST, WITH 2 SHORT AnD 5 LOnGER SETAE, ARTIcLE 3 WITH OnLY 2 InnER GROUPS OF 4 SETAE EAcH. Maxilla I ASYmmETRIc, PALPS nARROW, APIcALLY WITH cA. 5 STROnG SETAE OR SPInES. OUTER LObE WITH 10 SUbEqUAL, DEnSELY PEcTInATE SPInES WITH cA. 20 DEnTIcLES. Maxilla II AnD maxilliped WITHOUT PEcULIARITIES. GNATHOPODS ( FIGS 3A, B ). Gnathopod I ARTIcLE 6 nARROW AnD POORLY SETOSE, PALmAR AnGLE In ITS mIDDLE, ARTIcLE nOT PEAR-SHAPED; SHORT FAcIAL SETAE In cA. 5 GROUPS OF 1-3, SETAE ALOnG POSTERIOR AnD PALmAR mARGInS UP TO TWIcE LOnGER, bUT UP TO 5 GROUPS OF SETAE ALOnG POSTERIOR mARGIn WITH OnLY 2-5 SETAE EAcH; PALmAR SPInES WEAK; ARTIcLE 5, DISTAL HALF OF POSTERIOR mARGIn WITH 6 GROUPS OF SHORT SETAE, PARALLEL WITH AnTERIOR OnE. Gnathopod II ARTIcLES 5-6 ELOnGATED, THEIR POSTERIOR mARGInS PARALLEL WITH AnTERIOR OnES; ARTIcLE 5 WITH 8 GROUPS OF POSTERIOR AnD 2 GROUPS OF FAcIAL SETAE, AnTERIORLY OnLY WITH THE DISTAL SETAE; ARTIcLE 6 nARROW, WITH mODERATELY IncLInED PALmAR mARGIn, WITH 8 FAcIAL GROUPS OF 1-5 SETAE; OnE SLEnDER SPInE bETWEEn DAcTYLUS AnD THE SLEnDER PALmAR SPInE, POSTERIOR mARGIn WITH 7 GROUPS OF SETAE WHIcH ARE HALF SHORTER THAn THE ARTIcLE WIDTH. PEREOPODS ( FIGS 1A , 4A–E ). Pereopods III–IV WITH cA. 6-7 OnLY mODESTLY DEnSE GROUPS OF STIFF SETAE On ARTIcLES IV–VI POSTERIORLY, SETAE LEnGTHS On 4-5 UP TO DOUbLE ARTIcLE WIDTH, On VI SHORTER; DAcTYLUS APPROXImATELY 30% OF ARTIcLE 6 LEnGTH, nAIL cA. 40% OF DAcTYLUS LEnGTH. Pereopods V–VII ELOnGATED, THEIR LEnGTHS RELATIOn 10:11:11, THE VII IF EXTEnDED, REAcHInG TIPS OF UROPOD III, 70% OF bODY LEnGTH; bASES (ARTIcLES 2) nARROW, OnLY SLIGHTLY TAPERInG DISTALLY; DISTO-POSTERIOR LObES VERY SHORT, AcUTE; POSTERIOR mARGIn In VI–VII STRAIGHT, In V SLIGHTLY cOncAVE, EnDInG DISTALLY In SmALL REcTAnGULAR AnD AcUTE LObES; AnTERIOR mARGInS WITH 2-3 SPInES In THEIR DISTAL HALVES. ALOnG EAcH, AnTERIOR AnD POSTERIOR mARGInS OF ARTIcLE 4 2-4 PAIRS OF SPInES, In ARTIcLE 5 THERE ARE 4-6 SInGLE OR PAIRED; DAcTYLI cA. 20% OF ARTIcLE 6 LEnGTH, nAILS cA. 35% OF THE EnTIRE DAcTYLUS LOnG. PLEOPODS AND UROPODS ( FIGS 3C–E , 4F–H ). Pleopods nORmAL, RETInAcLES OF 2 HOOKED AnD 1-3 SHARP SPInES. Uropods I–II VERY LOnG, PEDUncLES WITH 2 SHORT FAcIAL AnD SOmE APIcAL SPInES, UROPOD I WITH A bASOFAcIAL SPInE; RAmI SHORTER THAn THE PEDUncLE, OnLY WITH VERY SHORT APIcAL SPInES; PEDUncLES REAcHInG cLOSE TO THE UROPOD III PEDUncLE EnD, RAmI bEYOnD THE mIDDLE OF UROPOD III RAmI. Uropod III PEDUncLE TWIcE AS LOnG AS WIDE, OnLY WITH SOmE SPInES DISTALLY; EXOPODITE WITH A mInUTE ARTIcLE 2, WITH mODERATELY LOnG PLUmOSE SETAE ALOnG bOTH mARGInS; EnDOPODITE cA. 85% OF EXOPODITE LOnG, SImILARLY SETOSE, bUT OUTER ROW WITH SImPLE SETAE.

Female. BODY 11.5 mm LOnG. Antenna I WITH 31 ARTIcLES. Gnathopods ( FIGS 5A, B ) SImILAR AS In mALE, jUST SLIGHTLY mORE SETOSE. Oostegites ( FIGS 5B–E ) cOmPARATIVELY nARROW, II 30 % AS WIDE AS LOnG , III– V nARROWER, mARGInAL SETAE In POSTERIOR OOSTEGITES AS LOnG AS THE PLATES WIDE . Pereopod V bASIPODITE WITH A SLIGHTLY PRODUcED AcUTE DISTO-POSTERIOR LObE. Uropod III AnD telson ( FIGS 5 F, G ) In ALL cHARAcTERS SImILAR AS In mALE, jUST SmALLER AnD LESS RIcHLY SETOSE .

Ecology and distribution. SUW OYUK (SUUVOYUK) 37.596778, 66.405500, ALT. 360 m nEAR GARLYK (KARLjUK), LEbAP PROVIncE, IS A cOLLAPSE SInKHOLE, An OPEnInG InTO DROWn cAVE SYSTEm. THE LAKE On THE SInK'S 'bOTTOm' IS In FAcT THE UPPER LAYER OF A DEEP SYSTEm OF KARST PHREATIc WATERS. SOmE InDIVIDUALS OF THE TROGLObIOTIc FISH Triplophysa starostini (PARIn) (SYn. Noemacheilus s., Paracobitis s., Troglocobitis s.) WERE ObTAInED SnORKELInG. SOmE InDIVIDUALS OF Gammarus WERE FOUnD PEnDInG On THE nET TRAP FOR cATcHInG FISHES, LEFT THERE OVERnIGHT. COnSIDERInG THE DIVER'S (M. PERELADOV) REPORT, SOmE SPEcImEnS OF THE PRObAbLE SUbTERRAnEAn STEnASELLID ISOPOD Stenasellus asiaticus BIRSTEIn ET STAROSTIn HAVE bEEn ObSERVED DEEPER. ALL OTHER AnImALS ARE REPRESEnTED bY nORmALLY PIGmEnTED EPIGEAn POPULATIOnS. In THE SHALLOWS OF THE bOTTOm LAKE THERE ARE SOmE AqUATIc PLAnTS AnD FILAmEnTOUS ALGAE, AS WELL AS EPIGEAn AqUATIc FAUnA IncLUDInG A SmALL POPULATIOn OF THE TOAD Bufotes cF. oblongus. GASTROPODA OnLY REPRESEnTED bY LYmnAEIDAE (cF. Radix SP.); OSTRAcODA (mAnY), CYcLOPOIDA (mAnY), CLADOcERA, COLEOPTERA DYTIScIDAE , LARVAE OF DIPTERA CHIROnOmIDAE (mAnY), TRIcHOPTERA, AT LEAST 2 SPEcIES OF ODOnATA FLYInG ( Ischnura cF. elegans, Orthetrum cF. coerulescens). HOWEVER, GAmmARIDS HAVE nOT bEEn SEEn In THIS LAYER.

Remarks. Gammarus troglomorphus , sp. n. IS A RATHER AbERRAnT EYELESS SPEcIES WITH EXTREmELY ELOnGATED APPEnDAGES AnD mODIFIED OUTER PLATE OF mAXILLA I. BY ELOnGATED APPEnDAGES IT RESEmbLES Gammarus microps PInKSTER ET GOEDmAKERS, 1975 KnOWn FROm A cAVE In MOROccO. BY LATERALLY cOmPRESSED AnD ELEVATED UROSOmITES IT RESEmbLES Gammarus syriacus CHEVREUX, 1895, Gammarus laborifer KARAmAn ET PInKSTER, 1977 AnD TO SEVERAL SImILAR SPEcIES KnOWn FROm THE MIDDLE EAST ( LEbAnOn, EGYPT, SYRIA AnD OTHER cOUnTRIES) (SEE ZAmAnPOORE et al. 2011). ITS EPImERA II APPEAR TO bE THE mOST PRODUcED In Gammarus . THE cHARAcTERISTIcS DISTInGUISHInG A nEW SPEcIES FROm THE PHYLOGEnETIcALLY cLOSE G. parvioculatus , sp. n. ARE DIScUSSED bELOW.

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 2. Gammarus troglomorphus, sp. n., male, 12.4 mm, holotype NC181: (А) antenna I; (B) antenna II; (C) mandible, left; (D) mandible, right; (E) maxilla I, left; (F) palp of maxilla I, right; (G) maxilla II; (H) upper lip; (I) lower lip; (J) maxilliped. Scale bars 0.2 mm.

FIGURE 3. Gammarus troglomorphus, sp. n., male, 12.4 mm, holotype NC181: (А) gnathopod I; (B) gnathopod II; (C) pleopod I; (D) pleopod II, part; (E) pleopod III, part; (F) epimeral plates; (G) urosoma, dorsal view. Scale bars 0.2 mm.

FIGURE 4. Gammarus troglomorphus, sp. n., male, 12.4 mm, holotype NC181: (А) pereopod III; (B) pereopod IV; (C) pereopod V; (D) pereopod VI; (E) pereopod VII; (F) uropod I; (G) uropod II; (H) uropod III; (I) telson. Scale bars 0.2 mm.

FIGURE 5. Gammarus troglomorphus, sp. n., female, 11.5 mm, paratype NC182: (А) gnathopod I; (B) gnathopod II; (C) pereopod III, part; (D) pereopod IV, part; (E) pereopod V, part; (F) uropod 3; (G) telson. Scale bars 0.2 mm.