Cymbasoma

Suárez-Morales, Eduardo & Mckinnon, David, 2016, The Australian Monstrilloida (Crustacea: Copepoda) II. Cymbasoma Thompson, 1888, Zootaxa 4102 (1), pp. 1-129 : 125-126

Key to the Australian species of Cymbasoma (females)

1A. Fifth leg with outer (exopodal) lobe armed with two setae..................................................... 2

1B. Fifth leg with outer (exopodal) lobe armed with three setae (the innermost sometimes shorter or narrower than the other two).................................................................................................... 6

2A. Body remarkably robust, globose, cephalothorax about 50% of total body length; inner lobe of fifth leg short, ball-like or platelike, robust; cephalothorax ornamented with dorsal patch or fringe of papillae-like elements..........................3

2B. Body relatively slender, cephalothorax representing more than 60 % of total body length; inner lobe of fifth leg digitiform; cephalothorax ornamented otherwise, with ventral field of transverse striae, a few ventral wrinkles or reticulated field..... 4

3A. Antero-ventral process of genital double-somite strongly developed, forming high thumb-like process visible in lateral view; terminal antennulary segment shorter than the length of the other segments combined; caudal setae proximally swollen; inner lobe of fifth leg wide, plate-like................................................... C. agoense Sekiguchi, 1982

3B. Antero-ventral process of genital double-somite absent, surface smooth in lateral view; terminal antennulary segment longer than the length of the other segments combined; caudal setae not swollen proximally; inner lobe of fifth leg reduced, ball-like................................................................................ C. tharawalorum sp. nov.

4A. Cephalic region with ventral protuberant process, ornamented with reticulated field or with field of deep, tight pattern of transverse striae.......................................................................................... 5

4B. Cephalic region with no ventral protuberances, ornamentation weak, represented by a few scattered wrinkles................................................................................................. C. lourdesae sp. nov.

5A. Inner lobe of fifth leg slender, relatively long, almost reaching to distal margin of outer lobe; oral papilla protuberant; ventral surface of cephalic region ornamented with field of tightly arranged transverse striae................. .. C. dakini sp. nov.

5B. Inner lobe of fifth leg short, barely reaching to middle margin of outer lobe; oral papilla poorly developed, not protuberant; cephalic region ornamented with fringe of reticulation............................................ Cymbasoma sp.

6A. Ovigerous spines proximally fused; genital double-somite quadrate, with deep dorsal striae; innermost seta of the fifth leg less than half the length of the outer setae..................................................... C. jinigudira sp. nov.

6B. Ovigerous spines separated at base; genital double-somite shaped and ornamented otherwise; innermost seta of the fifth leg slightly shorter or as long as the outer setae................................................................ 7

7A. Cephalothorax with band of transverse striations running around surface......................................... 8

7B. Cephalothorax with different ornamentation.............................................................. 10

8A. Band of striations covering more than 30% of cephalothorax; genital double-somite with rounded posterolateral processes.......................................................................................................9

8B. Band of striations covering less than 15% of cephalothorax, restricted to anterior cephalic region; genital double-somite with tapered distal half, processes absent.................................................... C. markhasevae sp. nov.

9A. Cephalothorax with band of striations covering ventral surface from bases of antennules to post-oral region, overall coverage being at least 45%; frontal margin smooth, with medial depression; ventral surface with “U”-shaped row of spinous processes.................................................................................... C. astrolabe sp. nov.

9B. Cephalothorax with band of striations covering ventral surface from bases of antennules to post-oral region, overall coverage being around 30%; frontal margin wrinkled, otherwise flat; ventral surface with usual ornamentation but no spinous processes.................................................................................. C. annulocolle sp. nov.

10A. Both anal somite and genital double-somite constricted, anal somite almost as long as or longer than genital double-somite 11

10B. Anal and genital double-somite not constricted, anal somite clearly shorter than genital double-somite................. 12

11A. Anal somite longer than genital double-somite; fifth pedigerous somite with dorsal field of deep transverse striations in posterior half; cephalothorax expanded in lateral view; antennulary segments 3–4 fused............... C. constrictum sp. nov.

11B. Anal somite slightly shorter than genital double-somite; fifth pedigerous somite with smooth dorsal surface; cephalothorax straight in lateral view; antennulary segments 3–4 separated.............................. C. paraconstrictum sp. nov.

12A. Genital double-somite with smooth posterior margin....................................................... 13

12B. Genital double-somite with two dentiform processes on posterior margin......................... C. bidentatum sp. nov.

13A. Fifth leg with inner lobe arising basally or at proximal 1/3 of inner margin of outer lobe........................... 15

13B. Fifth leg with inner lobe arising at halflength or subdistally with respect to the outer lobe............................ 14

14A. Fifth leg inner lobe rounded, at midlength of inner margin of outer lobe; dorsal surface of cephalic region with field of weak transverse wrinkles; anal somite with smooth dorsal and ventral surfaces, and smooth lateral margins.......................................................................................... C. bali Desai & Krishnaswamy, 1962

14B. Fifth leg inner lobe short, digitiform, arising subdistally from inner margin of outer lobe; dorsal surface of cephalic region with field of light reticulations; anal somite with corrugated lateral margins and striae on ventral surface..... C. apicale sp. nov.

15A. Fifth leg inner lobe digitiform, well-defined; legs 1–4 with 3-segmented exopods, legs 1–4 setae with normal aspect.... 16

15B. Fifth leg inner lobe not digitiform, represented by mere expansion of the inner margin of outer lobe; exopods of fourth leg 2- segmented, with dwarfed distal setae................................................. C. rafaelmartinezi sp. nov.

16A. Fifth leg inner lobe mammiliform.......................................................... C. buckleyi sp. nov.

16B. Fifth leg inner lobe not mammiliform..................................................................... 17

17A. Fifth leg inner lobe short, reaching at most to halfway down the outer lobe...................................... 18

17B. Fifth leg inner lobe not particularly short, reaching beyond halfway the length of the outer lobe..................... 19

18A. Frontal area with weak, not protuberant lens-like frontal processes; genital double-somite with small rounded processes along lateral margins of proximal half; fifth leg inner lobes short, reaching to halfway down the outer lobe, asymmetrical, one of them curved, the other bifurcate; antennules with segments 3–4 fused............................ C. fergusoni sp. nov.

18B. Frontal area with protuberant lens-like frontal processes; genital double-somite with smooth corrugate margins but no rounded processes along lateral margins of proximal half of somite; fifth leg inner lobes short, not reaching to halfway down the outer lobe, symmetrical; antennules with segments 3–4 separate..................................... C. lenticula sp. nov.

19A. Cephalic region with ventral field of transverse striae between oral papilla and insertion of antennules; nipple-like processes located midway between oral papilla and insertion of antennules; anal somite with corrugate lateral margins................................................................................................... C. tranteri sp. nov.

19B. Cephalic region with smooth ventral surface; nipple-like processes located at same level, next to oral papilla; anal somite with smooth lateral margins................................................................. C. solanderi sp. nov.