Gammarus parvioculatus, 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 : 445-449

Gammarus parvioculatus , sp. n.

FIGURES 1B , 6–8

Material examined. HOLOTYPE SPEcImEn NC183: mALE, 9.0 mm; SPRInG-cAVE, 37.94 3889, 66.612500, 1100 m A.S. L., KHODZHAPIL (HODžAPIL', HOjEYPIL), nEAR KOYTEn, KöýTEnDAG DISTRIcT, LEbAP PROVIncE, TURKmEnISTAn, LEG. 25 MAY 2015 bY B . SKET. PARATYPE NC184: FEmALE, 9.0 mm, OOSTEGITES DEVELOPED, SETOSE, bEARInG 6 mEDIUm-SIZED EGGS; UnDER SUbmERGED PLAnTS In LImnOcREnE; SAmE DATA AS HOLOTYPE .

OTHER SPEcImEnS EXAmInED FROm THE SAmE LOcALITY (nOT IncLUDED In THE TYPE SERIES): NC185-NC188: 4 mALES (4X 11.0 mm). PARTIALLY DISSEcTED, mEASURED AnD DEPOSITED AT THE RESEARcH cOLLEcTIOn OF THE ODDELEK ZA bIOLOGIjO, BIOTEHnIšKA FAKULTETA, UnIVERZA V LjUbLjAnI.

Diagnosis. STOUT, mEDIUm SIZED Gammarus WITH SLIGHTLY DImInISHED EYES; ALL APPEnDAGES cOmPARATIVELY SHORT; AnTEnnAE WITH SETAE SHORTER THAn ARTIcLE WIDTHS; mAXILLA I EXTERIOR LObE SPInES WEAKLY TO DEnSELY SERRATED; PEREOPODS III–IV WITH DEnSELY SETOSE ARTIcLES 4-6 POSTERIORLY; UROPOD III EnDOPODITE LOnGER THAn HALF EXOPODITE, ALL mARGInS WITH LOnG SETAE.

GenBank accession number: MG655629 FOR ISOLATE 515GPARVIOcTUM.

Etymology. SPEcIFIc EPITHET ' parvioculatus ' REFERS TO THE REDUcED SIZE OF EYES (parvus - SmALL In LATIn).

Description. GENERAL BODY MORPHOLOGY ( FIGS 1B , 7D, H, I ). Body STOUT. GEnAL PLATES SHORT, ROUnDED TRIAnGULAR, nEARLY SYmmETRIc UP-DOWn; EYES SmALL, SLIGHTLY SHORTER THAn AnTEnnAL ARTIcLE 1 WIDTH. Coxae I–IV LOnG (HIGH), I WIDEnED TOWARDS ITS APEX, IV LObATE; APIcAL mARGInS SLIGHTLY cOnVEX, I–II WITH cA. 5 DISTAnT, SmALL SETAE, III–IV WITH SETAE OnLY AT AnGLES. Pleonites WITH SmALL SETAE ALOnG DORSAL AnD LATERAL mARGInS, EPImERAL PLATES WITH 4-5 SmALL SPInES In THEIR APIcAL PARTS, epimeron II POSTERIORLY EnDInG REcTAnGULARLY, epimeron III SLIGHTLY AcUTE. Urosoma WITHOUT nOTIcEAbLE ELEVATIOnS, ITS mEDIAn SPInES AT THE POSTERIOR mARGInS, WIDELY DISTAnT mUTUALLY, WITH SOmE SHORT SETAE AmOnG SPInES; FORmULA FOR UROSOmITES I–III IS 1–1-1–1 // 2–1-1–2 // 2–2–2. Telson EqUALLY LOnG AS WIDE, DEEPLY SPLIT, EAcH LObE WITH 2 APIcAL AnD 1 bASO-mARGInAL SPInE, mODERATELY nUmEROUS APIcAL AnD FAcIAL SETAE UP TO 4X AS LOnG AS SPInES. ANTENNAE ( FIGS 1B , 6A, B ). Antenna I 57% bODY LEnGTH. PEDUncLE ARTIcLES In RELATIOn 10:7:5; ARTIcLES 1 AnD 3 WITH SHORT APIcAL SETAE, 2 ALSO WITH A GROUP In ITS mIDDLE; FLAGELLUm OF 27 ARTIcLES WHIcH ARE LOnGER THAn WIDE, WITH ROW OF SHORT (cA. 30% OF ARTIcLE LEnGTHS) SETAE ALOnG APIcAL mARGInS, IncLUDInG ALSO SInGLE EqUALLY SHORT AESTHETAScS. Antenna II cA. 50% PREVIOUS AnTEnnA LEnGTH, WITH LEnGTH RELATIOnS OF 4:5: FLAGELLUm AS 10:10:13; FLAGELLUm OF 9 ARTIcLES; ARTIcLES 4-5 WITH cA. 10 GROUPS OF SETAE EAcH (WITH STIFF nOTcHED SETAE On InnER FAcE), THEIR LEnGTH APPROXImATELY EqUAL THE WIDTH OF ARTIcLES; FLAGELLUm WITH TEnDER TUFTS OF SETAE On LATERAL mARGInS AnD APIcES OF ARTIcLES. MOUTH PARTS (TYPIcAL GAmmARID, FIGS 6C–J ). Mandible nORmAL, THE PALP WITH cA. 15 DIFFEREnTLY LOnG SETAE ALOnG THE ARTIcLE 2; ARTIcLE 3 WITH 2 FAcIAL GROUPS OF 2-4 SETAE. Maxilla I ASYmmETRIc, PALPS OnLY DISTALLY ARmED, LEFT PALP WITH cA. 10 SImPLE SETAE, RIGHT WITH 5 TEETH AnD 2 SETAE; OUTER LObE WITH cA. 12 SERRATED SPInES, InnER OnES WITH cA. 10, OUTER OnES WITH 3-4 DEnTIcLES. Maxilla II nORmAL, THE ObLIqUE ROW OF SETAE VERY cLOSE TO THE InnER mARGIn. GNATHOPODS ( FIGS 7A, B ). Gnathopod I mODERATELY SETOSE, ARTIcLE 5 TRIAnGULAR, WITH cLOSELY PRESSED POSTERIOR GROUPS OF SETAE AnD WITH OnE GROUP OF SETAE In THE mIDDLE OF THE AnTERIOR bORDER; ARTIcLE 6 WITH A VERY STEEP PALmAR mARGIn, PALmAR AnGLE nOT mARKED, WITH cA. 15 SmALL SPInES In THE AREA, nO LARGE SPInES PRESEnT; WITH 5 FAcIAL GROUPS OF 2-6 mODERATELY LOnG SETAE. Gnathopod II ARTIcLE 5 LOnGER, WITH 8 GROUPS OF SETAE ALOnG POSTERIOR mARGIn. SPInES In THE PALmAR AnGLE AREA LOnGER, LARGER SPInE In mIDDLE OF PALmAR bORDER, cA. 5 FAcIAL GROUPS OF 5-7 VERY LOnG SETAE. PEREOPODS ( FIGS 1B , 8A–E ). Pereopods III–IV WITH (EqUALLY) DEnSE bRUSHES OF LOnG (FOR DOUbLE ARTIcLE WIDTHS) SETAE ALOnG POSTERIOR mARGInS OF ARTIcLES 4-6. Pereopods V–VII In LEnGTH RELATIOn 100:116:112, VII 50 % OF bODY LEnGTH. WITH bASIPODITES ROUnDED AT AnGLES, V WITH mARKED DISTOPOSTERIOR AnGLE, VII WITH SLIGHTLY cOnVEX LOnGITUDInAL mARGInS, TAPERInG DISTALLY, WITH 3 SmALL SPInES AnD A TUFT OF SETAE ALOnG THE AnTERIOR AnD OVER 15 SmALL SETAE ALOnG POSTERIOR mARGIn; ARTIcLES 4-5 WITH 2 PAIRS OF PAIRED SPInES ALOnG mARGInS; DAcTYLUS cA. 25% OF ARTIcLE 6 LOnG, WITH A SHORT nAIL. PLEOPODS AND UROPODS ( FIGS 7C, E–G ). Pleopods nORmAL, PEDUncLE WITH SOmE GROUPS OF SETAE, RETInAcULA OF 2 HOOKED AnD 2-3 SLEnDER SImPLE SPInES. Uropods I–II PEDUncLES REAcHInG APPROXImATELY THE EnD OF UROSOmA, RAmI SLIGHTLY bEYOnD THE EnD OF UROPOD III PEDUncLE; PEDUncLES WITH cA. 4 SPInES ALOnG THE EDGES, UROPOD I WITH A bASOFAcIAL SPInE, WITH 1 OR 2 SInGLE OR PAIRED SPInES ALOnG RAmI, THEIR APIcAL SPInES mODERATELY LOnG, 5-6 In nUmbER. Uropod III PEDUncLE WITH A FAcIAL SPInE AnD SOmE SETAE AnD cA. 10 SPInES On THE APIcAL bORDER; EnDOPODITE 60% OF EXOPODITE LEnGTH, bOTH WITH mODERATELY DEnSE mARGInAL bRUSHES OF mODERATELY LOnG WITH mIX OF SImPLE AnD PLUmOSE SETAE.

Female. BODY 9.0 mm LOnG. Antenna I WITH 19 ARTIcLES. Gnathopod II PROPODUS SUb-REcTAnGULAR. 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.

Variability. In THE SUbTERRAnEAn bROOK, SOmE SPEcImEnS ARE PIGmEnTED, SOmE WITHOUT bODY PIGmEnTATIOn, bUT nO DIFFEREncE In EYE SIZE.

Ecology and distribution. CA. 10 InDIVIDUALS FOUnD WHERE A HOLE OF 2 m 2 OPEnS InTO A nARROW SUbTERRAnEAn cORRIDOR WITH A SHALLOW, WEAK (20 cm WIDE) STREAm. In THIS SmALL ILLUmInATED PART OF THE STREAm WAS FOUnD A DIVERSE EPIGEAn FAUnA: 'HYDRAcARInA', NEmATODA, OLIGOcHAETA, LARVAE OF DIPTERA SImULIIDAE (mAnY), CHIROnOmIDAE (mAnY), EPHEmEROPTERA (cF. Baetis, Caenis , EcDYOnURIDAE). OnLY OnE PIGmEnTED SPEcImEn ObTAInED In A DEnSE LUmP OF SUbmERSE PLAnTS In A LARGE LImnOcREnE.

Remarks. ALTHOUGH Gammarus parvioculatus , sp. n. IS ALSO RELATED TO A SUbTERRAnEAn HAbITAT, IT SHOWS nO TROGLOmORPHY EXcEPT THE SLIGHT EYE DImInUTIOn. EVEn In cOmPARISOn TO EPIGEAn SPEcIES IT IS VERY STOUT, WITH cOmPARATIVELY SHORT APPEnDAGES AnD WITH PARTIcULARLY RIcHLY SETOSE PEREOPODS III–IV. FROm G. troglomorphus , sp. n. IT ALSO DIFFERS bY ObTUSE EPImERA AnD A SmOOTH UROSOmA. Gammarus parvioculatus , sp. n. POSSESSES An InTERESTInG FEATURE OF AnTERIOR mARGIn OF cOXAE VI AnD VII bEARInG GROUPS OF SETAE AS In Gammarus parthicus STOcK, MIRZAjAnI, VOnK, NADERI ET KIAbI, 1998 (STOcK et al. 1998). WE cAn nOT EXcLUDE THAT THIS SPEcIES WAS REPORTED bY MARTYnOV (1935) UnDER THE nAmES Gammarus turanus subnivalis MARTYnOV, 1935, G. turanus karabasicus excisus MARTYnOV, 1935 AnD/OR G. turanus coxalis MARTYnOV, 1935 WHIcH ARE POORLY IDEnTIFIAbLE cRYOPHILIc SPRInG FORmS; bUT, G. parvioculatus , sp. n. WAS FOUnD PRETTY FAR FROm THE MARTYnOV'S AnImALS, AnD bESIDE THIS IT IS A mOLEcULARLY PROVEn cLOSE RELATIVE OF G. troglomorphus , sp. n.; ITS RELATIOn TO THE SUPPOSED G. subaequalis IS mUcH mORE DISTAnT. THE PAIR G. troglomorphus , sp. n. AnD G. parvioculatus , sp. n. ARE PHYLOGEnETIcALLY cLUSTERED TOGETHER (bUT POORLY SUPPORTED), ALOnG WITH G. decorosus MEnG, HOU ET LI, 2003 FROm XInjIAnG. ALTHOUGH THREE TURKmEn SPEcIES ARE GEOGRAPHIcALLY VERY cLOSE, jUST SOmE KILOmETERS APART, THEY ARE nOT cLOSELY RELATED. Gammarus troglomorphus , sp. n. AnD G. parvioculatus , sp. n. SPLIT FROm THE PROXImAL PART OF THE AGGREGATE cLADE. BOTH SPEcIES ARE mORPHOLOGIcALLY AmOnG THE mOST DISTAnT PAIRS WITHIn THE FORmAL GEnUS Gammarus .

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 6. Gammarus parvioculatus, sp. n., male, 9.0 mm, holotype NC183: (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, fragment; (J) maxilliped. Scale bars 0.2 mm.

FIGURE 7. Gammarus parvioculatus, sp. n., male, 9.0 mm, holotype NC183: (А) gnathopod I; (B) gnathopod II; (C) pleopod I; (D) epimeral plates; (E) uropod I; (F) uropod II; (G) uropod III; (H) telson; (I) urosoma, dorsal view. Scale bars 0.2 mm.

FIGURE 8. Gammarus parvioculatus, sp. n., male, 9.0 mm, holotype NC183: (А) pereopod III; (B) pereopod IV; (C) pereopod V; (D) pereopod VI; (E) pereopod VII. Scale bars 0.2 mm.