Ozestheria Schwentner & Richter, 2015

Genus Ozestheria Schwentner & Richter, 2015 View in CoL

Diagnosis (modified from Schwentner et al. 2015a and Rogers 2020)

Populations composed of males and females; amplexus is venter to venter. Umbo present, extending above dorsal margin (supramarginal). Carapace ornamentation highly variable, including lirae, reticulations or smooth ornamentation. Carapace coloration from yellow, to light brown, reddish-brown and dark brown. Head with condyle short or elongate, with wide or narrow occipital notch; frontal organ sessile. Rostrum without posterior margin. Juvenile with rostral spine, absent in adults. Claspers with slender, claw-like projections at the tip of the movable finger. Eggs attaching to prolonged exopods of thoracopods IX and X. Posterior trunk segments with several medial dorsoposterior spines per segment (very rarely last segment spineless). Cercopod with medial longitudinal setal row on proximal 40–60%. Setae plumose and either long or short. Setal row terminates with single spine.

Remarks

Rogers (2020) listed further diagnostic features, which we exclude from the genus diagnosis because these are either too variable to be diagnostic or we found that the range was greater than indicated in the diagnosis. For example, we excluded the character state “Ocular tubercle smoothly arcuate. Angle between rostrum and frons 150° to 170°.” ( Rogers 2020: 22), as the ocular tubercle can be variably expressed and the respective angle can vary from ~90° to 180°. Also, the height-length ratio is in fact much more variable than suggested in the diagnosis (“Carapace valve length ~1.5 times valve breadth (hinge to margin)”; Rogers 2020: 22).

Key to the Australian species of Ozestheria Schwentner, Just & Richter, 2015 View in CoL

One of the main characteristics is the length of the condyle, which had previously been used to separate the species into two genera, used here as the first distinguishing characteristic. Three species ( O. gemina sp. nov., O. carnegiensis sp. nov. and O. berneyi View in CoL ) had intermediate long condyles; therefore, these are listed twice.

1. Condyle short, rarely dorsally extending, always leaving wide occipital notch ( Fig. 25i View Fig ) ............... 2

– Condyle long, extending nearly to following trunk segment, leaving very narrow occipital notch ( Fig. 13b View Fig ); ornamentation on mid carapace never with well-defined polygonal reticulations ( Fig. 24e–g View Fig showing reticulations) .................................................................................................. 15

2. Carapace ornamentation dominated by distinctive polygonal reticulations, only crowded growth bands may lack these (and larval valve due to abrasion) ( Fig. 25g –h View Fig ).............................................. 3

– Carapace ornamentation not dominated by reticulations (these may be present dorsally on the carapace); ornamentation including lirae and/or nodules or smooth............................................... 10

3. Ventral margin of carapace nearly straight ( Fig. 25b View Fig ); telsonic spines usually small ( Fig. 25m View Fig ) (larger spines mainly in juveniles) ............................................................................................................... 4

– Ventral margin of carapace widely rounded, not straight ( Fig. 15a View Fig ); telsonic spines usually of varying size (including larger spines also in adults) ....................................................................................... 5

4. 24–27 complete thorax segments; adult telson usually with <15 spines (rarely exceeding 15, juveniles with more spines); largest known Australian species of Ozestheria View in CoL , adults usually exceeding 10 mm ......................................................................................... O. lutraria ( Brady, 1886) View in CoL

– 23–24 complete thorax segments; adult telson with>15 spines; adults reach ~ 9 mm ....................... ....................................................................................................................... O. paralutraria sp. nov.

5. Walls of polygonal ornamentation not regular, single polygons often intermittent or with projections ( Fig. 15e View Fig ); known only from south-eastern Australia........................................ O. christiani sp. nov.

– Walls of polygonal ornamentation never intermittent or with lateral projections, polygons with pit-like appearance ( Fig. 22e View Fig ).................................................................................................................. 6

6. Carapace ornamentation with polygons, which decrease in size and are slightly compressed ventrally within growth bands ( Fig. 43a, f View Fig ); secondary carapace ornamentation pit-like/rounded (visible best under SEM); male rostrum shorter and concentric ridges of carapace less strongly demarcated than in other species; known only from central Western Australia ........................ O. sarsii ( Sayce, 1903) View in CoL

– Carapace ornamentation with polygons, which are not compressed ventrally within growth bands ( Fig. 22e–g View Fig ); secondary carapace ornamentation polygonal (visible best under SEM); male rostrum longer (more elongated) and concentric ridges of carapace stronger demarcated than in other species dominated by polygonal ornamentation (the following species are difficult to distinguish morphologically)................................................................................................................................ 7

7. Telson with more spines (> 20, up to 30); shorter carapace (length up to 7 mm); male antennule short, reaching to flagellomeres V–VII (unknown for O. elliptica View in CoL ) ............................................................ 8

– Telson with fewer spines (usually ~20, rarely up to 27); longer carapace (up to 9 mm, but not all individuals reach this size); male antennule longer, reaching to flagellomeres VII–X ..................... 9

8. Spines on mid telson slightly enlarged; furca with several setae; known only from northern Queensland ........................................................................................................... O. henryae sp. nov.

– All telsonic spines subequal in length; furca without setae; known only from north-eastern Western Australia ......................................................................................................... O. elliptica ( Sars, 1897) View in CoL

9. 22–23 complete thorax segments; male rostrum apex strongly rounded; occurs in central and eastern Australia.......................................................................................................... O. rubra ( Henry, 1924) View in CoL

– 22–24 complete thorax segments; male rostrum apex weakly rounded; occurs in Western Australia ................................................................................................................ O. matuwa sp. nov.

10. Male rostrum apex rounded ( Fig. 14h View Fig ); thorax with ≤ 21 complete segments .................................11

– Male rostrum apex pointed (acute angle) or protruding ( Fig. 42j View Fig ); thorax with ≥ 22 complete segments .......................................................................................................................................... 13

11. Carapace ornamentation on wide growth bands dominated by punctae ( Fig. 14f View Fig ); large number of mostly crowded growth bands (>50); only known from central Western Australia ........................... ....................................................................................................................... O. carnegiensis sp. nov.

– Carapace ornamentation on wide growth bands smooth, nodular, with depressions and/or lirae; carapace usually with <20 growth bands ........................................................................................ 12

12. Carapace ornamentation granular, nodular and pit-like, lacking lirae; carapace coloration whitish translucent; furca with many (~14) setae; only known from northern Western Australia ................... .................................................................................................................... O. pellucida Timms 2018 View in CoL

– Carapace ornamentation dorsally smooth or with irregular depressions, from mid-carapace irregular, nodulous and inconspicuous lirae; carapace coloration dark brown (ventrally lighter); furca with few (~1) setae; only known from western Western Australia ....................................... O. richteri sp. nov.

13. Rostrum with small wing-like dorsal flange, anterior margin strongly convex in males, apex protruding ( Fig. 42j View Fig ); carapace length up to 10 mm; known only from central Western Australia ..... .......................................................................................................................... O. rufa ( Dakin, 1914) View in CoL

– Rostrum lacking dorsal flange, anterior margin straight or weakly convex, apex pointed or weakly rounded (not protruding) ( Fig. 20j View Fig ); carapace length <8 mm ......................................................... 14

14. Mid-carapace ornamentation includes reticulations dorsally within growth bands, which transition into lirae..................................................................................................... O. berneyi ( Gurney, 1927) View in CoL

– Mid-carapace ornamentation dominated by dorsally anastomosing lirae, no reticulations................. ............................................................................................................................... O. gemina sp. nov.

15. Carapace ornamentation dorsally within growth bands smooth ( Fig. 45e View Fig ) ..................................... 16

– Carapace ornamentation dorsally within growth bands with lirae, granular or punctate, never smooth.............................................................................................................................................. 19

16. Most growth lines densely covered with stout setae ( Fig. 45g View Fig ); male rostrum anterior margin convex and apex strongly rounded ( Fig. 45j View Fig )............................................................................................... 17

– Setae predominately preserved ventrally and posteriorly on carapace (others broken off); male rostrum anterior margin nearly straight and apex weakly rounded and tapered ( Fig. 46i View Fig ).............. 18

17. Mid-carapace ornamentation with short, partly nodulous lirae ventrally within growth bands; setae mid-long; known from southern Queensland and northern New South Wales ..... O. setifera sp. nov.

– Mid-carapace ornamentation smooth and only with remnant lirae very close to the concentric ridge; setae very long; known from Western Australia ................................................... O. echidna sp. nov.

18. Mid-carapace ornamentation with highly anastomosing short lirae ventrally within growth bands, lirae separated by punctae; dorsally smooth area within growth bands increases in extension with each growth band; 19–21 complete thorax segments; female rostrum apex weakly pointed; no tubercle on ocular tubercle...................................................................................... O. sivesae sp. nov.

– Mid-carapace ornamentation with short parallel lirae ventrally within growth bands; dorsally smooth area within growth bands decreases in extension with each growth band; 19–23 complete thorax segments; female rostrum apex drawn out into acute tip; most individuals with small tubercle on ocular tubercle .......................................................................................................... O. jiangi sp. nov.

19. All or at least posterior ½ of telsonic spines long, elongated and aciculate (longer than anterior conical spines) ( Fig. 30h–i View Fig ); telson dorsal margin often strongly concave (following species are difficult to differentiate morphologically) ....................................................................................... 20

– Majority of telsonic spines short and conical, elongated and aciculate spines only posteriorly on telson (or not much longer than conical spines) ( Fig. 47m View Fig ); telson dorsal margin convex, straight or weakly concave (never strongly concave)....................................................................................... 25

20. Apex female rostrum terminating in elongated, slightly wider tip ( Fig. 31c, e View Fig ) ............................. 21

– Apex female rostrum terminating in short, minutely pointed tip ( Fig. 37i View Fig ) .................................... 22

21. Anterior margin of rostrum straight in males and straight to weakly concave in females; mid-carapace lirae nodular in later juvenile stages ................................................................... O. minor comb. nov

– Anterior margin of rostrum convex or straight in males and weakly concave and/or undulating in females.................................................................................................................... O. selmae sp. nov.

22. Male rostrum anterior margin concave; only occurring in Western Australia ....... O. radiata sp. nov.

– Male rostrum anterior margin straight or weakly undulating or convex ......................................... 23

23. Male rostrum anterior margin straight or weakly undulating; occurring only in central Western Australia ..................................................................................................... O. beleriandensis sp. nov.

– Male rostrum anterior margin convex ............................................................................................. 24

24. Telson with more spines (18–32); lirae well developed in mid-carapace; occurring in Western Australia, Northern Territory, South Australia and New South Wales ............... O. typica comb. nov.

– Telson with fewer spines (17–24); lirae heavily anastomosing and inconspicuous in mid-carapace; occurring only in northern New south Wales .................................................. O. bourkensis sp. nov.

25. 23 or more complete thorax segments............................................................................................. 26

– 23 or fewer complete thorax segments ............................................................................................ 29

26. Male and female rostrum with strongly rounded apex, angle≥90°( Fig.47j–k View Fig );large carapace(reaching 8–11.5 mm); carapace ornamentation dominated by large, conspicuous punctate (with lirae forming in between in later growth bands); known only from northern Queensland .......... O. timmsi sp. nov.

– Male and female rostrum with pointed or weakly rounded apex, angle <90° ( Fig. 20 j–k View Fig ); mid-sized carapace (reaching 4.5–8 mm); carapace ornamentation dominated by lirae, punctae present but tiny and poorly visible ............................................................................................................................ 27

27. Mid-carapace ornamentation dominated by dorsally anastomosing lirae, no reticulations................. ............................................................................................................................... O. gemina sp. nov.

– Mid-carapace ornamentation includes reticulations (sometimes pit-like) dorsally within growth bands, which transition into lirae ( Fig. 34d–g View Fig )................................................................................ 28

28. Apex of female rostrum pointed and drawn out into protruding tip; 4–5 short setae between two long setae on concentric ridges; reticulations on mid-carapace well defined and regular; known from central and eastern Australia...................................................................... O. berneyi ( Gurney, 1927)

– Apex of female rostrum pointed but not drawn out; short and long setae alternating or irregularly arranged on concentric ridges; reticulations on mid-carapace poorly defined and pit-like; known only from Western Australia ............................................................................ O. pilbarensis sp. nov.

29. Angle between ocular tubercle and rostrum ~90° ( Fig. 27i–j View Fig ) ........................................................ 30

– Angle between ocular tubercle and rostrum obtuse (> 120°) or nearly straight (rarely close to 90°). ......................................................................................................................................................... 32

30. Male antennule with ≤ 11 lobes; antenna with ~10 flagellomeres; hump at base of condyle; nauplius eye small ..................................................................................... O. mariae ( Olesen & Timms, 2005)

– Male antennule with ≥ 11 lobes; antenna with ≥ 12 flagellomeres; no hump at base of condyle; nauplius eye large ............................................................................................................................ 31

31. Can reach>50 crowded growth lines; condyle distally rounded; carapace ornamentation dominated by punctae, only short and inconspicuous lirae ............................................. O. carnegiensis sp. nov.

– Up to 10 crowded growth lines; condyle distally acute; carapace ornamentation with punctae, but irregular lirae well visible (especially ventrally within growth bands)............. O. quinlanae sp. nov.

32. Ocular tubercle well developed in males ( Fig. 50h View Fig ); hump at base of condyle present.................. 33

– Ocular tubercle weakly developed in males ( Fig. 18i View Fig ); hump at base of condyle present or absent... ......................................................................................................................................................... 35

33. Male rostrum apex with acute angle; male antennule with ~16 lobes; known only from south-eastern Australia (South Australia and New South Wales)........................................... O. rincewindi sp. nov.

– Male rostrum with right or obtuse angle; male antennule with <15 lobes ..................................... 34

34. Line between condyle and ocular tubercle strongly concave; thorax with 21 complete segments; known only from northeastern Queensland ............................................... O. barcaldinensis sp. nov.

– Line condyle-ocular tubercle straight or only weakly concave; thorax with 19–20 complete segments; known only from Western Australia ....................................................................... O. weeksi sp. nov.

35. Carapace ornamentation: nodular lirae absent, lirae continuous ( Fig. 12e–g View Fig ) ................................ 36

– Carapace ornamentation: nodular lirae present ( Fig. 19e View Fig )............................................................... 40

36. ≥ 20 (usually ≥21) complete thorax segments................................................................................. 37

– ≤ 20 complete thorax segments........................................................................................................ 39

37. 22–31 telsonic spines; known from southern Queensland .............................. O. frederikeae sp. nov.

– 9–24 telsonic spines......................................................................................................................... 38

38. Female rostrum lacking dorsal indentation in anterior margin and straight or weakly concave ventral margin; widely distributed and common in central and eastern Australia... O. cancellata comb. nov.

– Female rostrum with dorsal indentation in anterior margin and convex ventral margin; known from northern Queensland ............................................................................................... O. jonnae sp. nov.

39. Angle between male ocular tubercle and rostrum nearly straight; male rostrum anterior margin straight or weakly concave, apex pointed; known from central Western Australia ....... O. ngamurru sp. nov.

– Angle between male ocular tubercle and rostrum obtuse (~120°); male rostrum anterior margin dorsally concave, apex strongly rounded; known from central Western Australia .............................. ................................................................................................................................. O. glabra sp. nov.

40. Carapace ornamentation dorsally on carapace (early and late juvenile) with polygonal reticulations, nodular lirae on mid-carapace more pronounced; female rostrum lacking distinct rounded bulge at fronto-dorsal corner; mid-ventral margin of rostrum nearly straight; known from central Queensland .......................................................................................................... O. fuersichi sp. nov.

– Carapace ornamentation dorsally on carapace (early and late juvenile) punctate or granular, lirae on mid-carapace inconspicuous; female rostrum with distinct rounded bulge at fronto-dorsal corner; known only from mountainous regions of southern New South Wales ............... O. marthae sp. nov.