Korealona, Jeong & Sinev & Brancelj & Chang & Kotov, 2017

Jeong, Hyun Gi, Sinev, Artem Y., Brancelj, Anton, Chang, Kwang-Hyeon & Kotov, Alexey A., 2017, A new blind groundwater-dwelling genus of the Cladocera (Crustacea: Branchiopoda) from the Korean Peninsula, Zootaxa 4341 (4), pp. 451-474 : 454-455

Korealona gen. nov.

Etymology. THE NAME “ Korealona ” IS cOMPOSED OF THE cOUNTRY NAME WHERE THE GENUS WAS FOUND AND THE GENUS NAME Alona, TYPE GENUS OF THE FAMILY ALONINAE .

Type species. Korealona karanovici gen.nov., sp.nov.

Diagnosis. Female. BODY SMALL, MAXIMUM LENGTH OF ADULT FEMALE 0.36 MM. BODY cOLOURLESS, LOW OVAL, MODERATELY cOMPRESSED LATERALLY. MAXIMUM HEIGHT AT MID-bODY. CARAPAcE AND HEAD SHIELD WITHOUT A KEEL, VALVES FROM PREVIOUS MOLTS NEVER RETAINED. DORSAL, POSTERIOR AND VENTRAL MARGINS OF VALVES EVENLY cURVED; POSTERO-DORSAL, POSTERO-VENTRAL AND ANTERIOR-VENTRAL ANGLES OF VALVES bROADLY ROUNDED. POSTERO-VENTRAL ANGLE OF VALVES WITHOUT DENTIcLES; VALVE SURFAcE SMOOTH. HEAD SMALL, TRIANGULAR IN LATERAL VIEW; ROSTRUM SHORT, POINTING DOWNWARD. COMPOUND EYE AND OcELLUS NOT DIScERNIbLE. HEAD SHIELD OF MODERATE WIDTH, WITH ELONGATED ROSTRUM; POSTERIOR MARGIN OF HEAD SHIELD bROADLY ROUNDED. THREE MAJOR HEAD PORES, WITH A NARROW cONNEcTION. LATERAL HEAD PORES MINUTE, LOcATED VERY cLOSE TO MAJOR PORES. LAbRUM WITH A MODERATELY bROAD KEEL; KEEL APEX ROUNDED, POSTERIOR MARGIN OF KEEL WITHOUT ANY SETULAE. THORAX TWO TIMES LONGER THAN AbDOMEN. AbDOMEN WITHOUT AbDOMINAL JOINT, MIDDLE AbDOMINAL SEGMENT NOT SADDLE-SHAPED. POSTAbDOMEN RELATIVELY SHORT AND NARROW, NARROWING IN ITS POSTANAL PART. VENTRAL MARGIN STRAIGHT. DISTAL MARGIN AND DISTAL ANGLE NOT DEVELOPED, DORSAL MARGIN cOMING TO bASIS OF cLAWS. DORSAL MARGIN WEAKLY cONcAVE TO STRAIGHT IN ANAL PORTION, STRAIGHT OR WEAKLY cONVEX IN POSTANAL PORTION. PREANAL ANGLE WELL-DEFINED, POSTANAL ANGLE ILL-DEFINED. POSTANAL MARGIN WITH AbOUT FIVE NARROW MARGINAL TEETH ON ANTERIOR MARGIN. LATERAL FAScIcLES OF SETULAE WEAKLY DEVELOPED, ALL SETULAE IN EAcH FAScIcLE OF SIMILAR LENGTH AND THIcKNESS, SHORTER THAN MARGINAL TEETH. POSTAbDOMINAL cLAW OF MODERATE LENGTH, WEAKLY cURVED. BASAL SPINE RELATIVELY SHORT. ANTENNA I ELONGATED, NOT PROTRUDING bEYOND TIP OF ROSTRUM. ANTENNULAR SENSORY SETA THIN, LONG. NINE TERMINAL AESTHETAScS OF VARIAbLE LENGTH, LONGEST ALMOST AS LONG AS ANTENNA I ITSELF . ANTENNA II WITH ANTENNAL FORMULA: SETAE 0– 0–3/1–1–3; SPINES 1–0–1/0–0–1. BASAL SEGMENT RObUST, bRANcHES SHORT, ALL SEGMENTS cYLINDRIcAL; PROXIMAL SEGMENT OF EAcH bRANcH 1.5 TIMES LONGER THAN EAcH OF TWO OTHER SEGMENTS. SPINES OF PROXIMAL SEGMENT OF EXOPOD VERY SHORT; APIcAL SPINES SHORTER THAN APIcAL SEGMENTS.

LIMb I. AccESSORY SETA LONG OR SHORT. IDL WITH TWO SETAE, SETA 1 AbSENT, SETAE 2 AND 3 OF SIMILAR SIZE, ARMED WITH THIN SETULAE IN DISTAL PORTION. ENDITE 4 WITH FOUR SETAE. ENDITE 3 WITH THREE POSTERIOR SETAE AND A SHORT ANTERIOR SETA. ENDITE 2 WITH TWO bI-SEGMENTED SETAE AND AN ANTERIOR SETA LONGER THAN ANTERIOR SETA OF ENDITE 3. VENTRAL SURFAcE OF LIMb WITH ROWS OF LONG SETULAE. TWO EJEcTOR HOOKS, OF UNEQUAL SIZE. MAXILLAR PROcESS (ENDITE 1) WITH A SINGLE SETA.

LIMb II. EXOPODITE NARROW, ELONGATED, WITH OR WITHOUT SETA. INNER PORTION OF LIMb WITH EIGHT THIN ScRAPING SPINES, ARMED WITH THIN SETULAE. DISTAL ARMATURE OF GNATHObASE WITH FOUR ELEMENTS. FILTER PLATE II WITH SIX SETAE.

LIMb III. EXOPODITE ROUNDED, WITH SEVEN MARGINAL (INNER) SETAE, SETA 3 LONGEST, SETAE 6–7 OF MODERATE LENGTH, SETAE 1–2 AND 4–5 VERY SHORT. SETAE 1–5 PLUMOSE, SETAE 6–7 ARMED WITH SHORT SETULAE OR NAKED. DISTAL ENDITE WITH THREE MARGINAL SETAE, TWO DISTALMOST ONES SLENDER, SHARP, WITH DENTIcLES; bASALMOST SETA SHORTER, GENIcULATED, WITH THIN SETULAE. BASAL ENDITE WITH FOUR STIFF SETAE. FOUR SOFT POTERIOR SETAE INcREASING IN SIZE bASALLY. DISTAL ARMATURE OF GNATHObASE WITH FOUR ELEMENTS: ELONGATED, cYLINDRIcAL SENSILLUM; THIN, GENIcULATED SETA; AND TWO SHORT POINTED SPINES. FILTER PLATE III WITH SEVEN SETAE.

LIMb IV. EXOPODITE NARROW, ELONGATED, WITH SIX PLUMOSE SETAE. PROPORTIONS OF SETAE VARY AMONG SPEcIES, bUT SETA 3 ALWAYS VERY SHORT. INNER PORTION OF LIMb IV WITH FOUR MARGINAL (ANTERIOR) SETAE AND A SMALL SENSILLUM. DISTALMOST SETA (1) LONG AND THIN, FLAMING-TORcH SETAE OF SIMILAR MORPHOLOGY, WITH NARROW bASES. THREE SHORT POSTERIOR SOFT SETAE INcREASING IN SIZE bASALLY. GNATHObASE WITH A LONG bI-SEGMENTED SETA. FILTER PLATE IV WITH FOUR SETAE.

LIMb V. EXOPODITE V SMALL, ROUND, WITH FOUR PLUMOSE SETAE. INNER LObE MODERATELY bROAD, LARGER THAN EXOPODITE. AT INNER FAcE, TWO SHORT SETAE OF SIMILAR SIZE AND A bLUNT PROcESS. FILTER PLATE V AbSENT.

Male. BODY SLIGHTLY LOWER THAN IN FEMALE, SUb-REAcTANGULAR, WITH A STRAIGHT DORSAL MARGIN IN ITS POSTERIOR HALF. POSTAbDOMEN SHORTER THAN IN FEMALE, STRONGLY NARROWING DISTALLY IN POSTANAL PORTION, WITHOUT DEFINED DISTAL ANGLE. BOTH PREANAL AND POSTANAL ANGLES WEAKLY DEFINED. GONOPORES LOcATED AT VENTRAL MARGIN, AT 1/4 MARGIN LENGTH FROM THE END OF POSTAbDOMEN. POSTERIOR MARGIN WITH A SINGLE MARGINAL DENTIcLE AND A cLUSTER OF SETULAE. LATERAL FAScIcLES OF SETULAE AS IN FEMALE . POSTAbDOMINAL cLAW SLIGHTLY SHORTER THAN IN FEMALE, SLIGHTLY cURVED, WITH A SHORT bASAL SPINE. ANTENNA AS LONG AS IN FEMALE . LIMb I WITH U-SHAPED cOPULATORY HOOK.

Differential diagnosis. THE MAIN DIAGNOSTIc FEATURE OF Korealona gen. nov., SEPARATING IT FROM THE OTHER REPRESENTATIVES OF ALONINAE , IS THE AbSENcE OF cOMPOUND EYE AND OcELLUS. A VERY SMALL, ROUND EXOPODITE V WITH VERY SHORT SETAE IS ALSO A UNIQUE DIAGNOSTIc FEATURE OF Korealona gen. nov. WITHIN ALONINAE , cOMPLETE AbSENcE OF cOMPOUND EYE AND OcELLUS IS REPORTED ALSO FOR Brancelia AND Spinalona CIROS-PÉREZ & ELíAS-GUTIÉRREZ, 1997.

Brancelia DIFFERS FROM Korealona gen. nov. IN: 1) A HIGHER bODY; 2) DIFFERENT SHAPE OF POSTAbDOMEN; 3) WELL- DEVELOPED IDL SETA 1 ON LIMb I, WHIcH IS AbSENT IN Korealona gen. nov.; 4) EXOPODITE II WITH A LONG SETA, WHIcH IS SHORT/AbSENT IN Korealona gen. nov. AND 5) bI-LObED EXOPODITE V WHIcH IS SMALL AND ROUND IN Korealona gen. nov.

Spinalona, ANOTHER bLIND ALONINE, IS SUPERFIcIALLY SIMILAR TO Korealona gen. nov. DUE TO A SHORT, STRONGLY TAPERING DISTALLY POSTAbDOMEN WITH A VERY LONG PREANAL MARGIN AND A VERY LONG bASAL SPINE ON THE POSTAbDOMINAL cLAW. BUT Spinalona (SEE CIROS-PÉREZ & ELíAS-GUTIÉRREZ 1997; KOTOV & ELíAS-GUTIÉRREZ 2002) DIFFERS FROM Korealona gen. nov. IN: 1) LATERAL HEAD PORES LOcATED VERY FAR FROM MAJOR PORES; 2) ROW OF MARGINAL SETAE REAcHING THE POSTERIOR 1/4 OF THE VENTRAL MARGIN; 3) A DIFFERENT SHAPE OF POSTAbDOMEN, E.G. WELL-EXPRESSED PREANAL AND POSTANAL ANGLES OF POSTAbDOMEN; 4) PRESENcE OF SEVERAL VERY STRONG SPINULAE NEAR bASAL SPINE ON THE POSTAbDOMENAL cLAW; 5) STRONG APIcAL SPINES AND SPINE ON THE PROXIMAL ENDOPOD SEGMENT, PLUS PRESENcE OF A SERIES OF LONG SETULAE ON THE SEGMENTS OF bOTH bRANcHES; 6) VERY LONG SETAE OF ODL AND IDL OF LIMb I; 7) PRESENcE OF A WELL-DEVELOPED IDL SETA 1 ON LIMb I, WHIcH IS AbSENT IN Korealona gen. nov.; 8) AbSENcE OF A SETA ON EXOPODITE II; 9) EXOPODITE III WITH ONLY FOUR SETAE, bUT 6 IN Korealona gen. nov.; 10) VERY DIFFERENT PROPORTIONS bETWEEN SETA SIZES ON EXOPODITE IV; 11) EXOPODITE V WITH THREE LONG SETAE, WHILE Korealona gen. nov. HAS FOUR SHORT SETAE.