Key to Generic Exemplars of Australian Phreatoicidea (Crustacea, Isopoda)

G.D.F. Wilson & S.J. Keable, Australian Museum

 

CONTENTS

Taxonomic Assumptions. This key is neither a key to all species nor a key to all genera of Australian phreatoicideans. We currently are using Nicholls’ (1943, 1944) genera without change because their defining synapomorphies (derived character states shared by all members) are unclear. Because the genera are inadequately defined, an exemplar (example species) of most genera has been provided, with 2 exceptions: Colacanthotelson rugosus and Paraphreatoicus relictus are not in the database. The speciose genus Colubotelson has taxa from both Victoria and from Tasmania. The Tasmanian species of Colubotelson may be transferred to different genera. Some species included in the key are undescribed (e.g., Eophreatoicus sp. 6), or have not been definitely associated with a described species. As a result of these uncertainties, a taxon that keys out to a particular species in this key should be assigned only to the associated genus. In most cases, the species diversity in these genera is much higher than currently described in the literature. GoTo Top

Interactive Identification. We assume that the user is already be familiar with the DELTA program INTKEY. The three files required (Intkey.ini, ichars, iitems) should be on the disk of a computer that has INTKEY program installed. These files, compressed into a ZIP file (phreakey.zip), are available from this website (download below) and planned to be available on the Australian Museum web site by next year. Users should get the most recent version because we will be regularly improving the taxonomic coverage of the database. Our eventual (but not immediate) goal is to score all described species into the database. We have provided a geographic "cheat" for preselecting taxa because many genera are found only in one or two states. By selecting "Include taxa" (or typing the command in the DOS version), select one of the following: Australia, Victoria+NSW, Western Australia, Tasmania, New Zealand. Minimally "Australia" should be chosen to avoid getting a non-Australian species. The "Tasmania" and "Victoria+NSW" sets should be used with care because many species from these states are not yet in the database. For example, Phreatoicoides has a currently unscored species from Tasmania. Taxa may be identified from external morphology by selecting characters from the "BEST" choices. Easily seen features may be USEd initially, such as whether the eyes are present or absent. See the plates for a guide to phreatoicidean morphology. GoTo Top

Download Interactive Key. Instructions: shift-click to save, unzip, then open intkey.ini with the DELTA (DEscription Language for TAxonomy) program IntKey GoTo Top

Traditional Key. This key was generated by the DELTA program KEY from our database of phreatoicidean species as of 28 January 1999. The dataset has 553 characters, 28 of which are used in the key, with 24 species reported in this key. Most characters can be determined from the external morphology but a few, like the mandible and the male pleopod, require some dissection. See the plates for a guide to phreatoicidean morphology. The couplets in this key are numbered, with the parenthetic number showing the previous couplet to ease backtracking. GoTo Top

 

1. (fig) Telsonic region lateral lobes absent

2

Telsonic region lateral lobes forming vertical plate

11

Telsonic region lateral lobes forming rounded setose lobe

16

2(1). (fig) Eyes present; mandibular notch on head present

3

Eyes vestigial, or absent; mandibular notch on head absent

7

3(2). (fig) Telsonic region or tail piece median lobe entire; mandibular right lacinia mobilis absent, all spines in spine row similar in position, size and shape (fig); telsonic region median lobe reflexed dorsally

4

Telsonic region or tail piece median lobe broadly indented; mandibular right lacinia mobilis large, well separated and distinct from spine row; telsonic region median lobe not reflexed

Phreatoicopsis terricola Spencer & Hall, 1896

4(3). (fig) Uropodal protopod dorsomedial ridge not produced

5

Uropodal protopod dorsomedial ridge produced

6

5(4). (fig) Male pleopod II endopod appendix masculina distal tip truncate; uropodal protopod ventral ridge long simple setae projecting laterally sparse; penes extending near midline (fig)

Onchotelson brevicaudatus (Smith, 1909)

Male pleopod II endopod appendix masculina distal tip broadly rounded; uropodal protopod ventral ridge long simple setae projecting laterally absent; penes extending past midline and onto pleonite 1

Mesacanthotelson tasmaniae (Thomson, 1894)

6(4). (fig) Penes distal tip rounded; male pleopod II endopod appendix masculina distal tip truncate; uropodal protopod ventral ridge long simple setae projecting laterally sparse

Onchotelson brevicaudatus (Smith, 1909)

Penes distal tip truncate; male pleopod II endopod appendix masculina distal tip broadly rounded; uropodal protopod ventral ridge long simple setae projecting laterally absent

Uramphisopus pearsoni Nicholls, 1943

7(2). (fig) Uropodal protopod dorsomedial ridge not produced; male pleopod II endopod appendix masculina ventral shape of cross section of proximal half of shaft concave (forming an elongate trough) (fig); pleotelson dorsal uropodal ridge present (fig)

8

Uropodal protopod dorsomedial ridge produced; male pleopod II endopod appendix masculina ventral shape of cross section of proximal half of shaft convex (flattened in cross section); pleotelson dorsal uropodal ridge absent

9

8(7). (fig) Telsonic region or tail piece median lobe entire; right lacinia mobilis large, well separated and distinct from remainder; pleonites in lateral view much deeper than pereonites, with large pleurae, basal region of pleopods not visible

Crenisopus acinifer Wilson & Keable, ms name 1999

Telsonic region or tail piece median lobe broadly indented; right lacinia mobilis absent, all spines in spine row similar in position, size and shape; pleonites in lateral view having depth approximating depth of pereonites, with small or absent pleurae, basal region of pleopods visible

Hypsimetopus sp. (near Zeehan, Tasmania)

9(7). (fig) Uropod protopod dorsomedial ridge bump with robust setae; male pleopod I exopod dorsal surface with setae; pereopod I dactylus subequal to palm in female

Pilbarophreatoicus Knott & Halse, in press sp.1 (Millstream aquifer, W.A.)

Uropod protopod dorsomedial ridge spur or spine-like; male pleopod I exopod dorsal surface lacking setae; pereopod I dactylus shorter than palm in female

10

10(9). (fig) Uropodal endopod dorsal margin robust spine absent; cervical groove on head absent; clypeal notch on head absent

Hyperoedesipus plumosus Nicholls & Milner, 1923

Uropodal endopod dorsal margin robust spine present; cervical groove on head smoothly curved; clypeal notch on head present

Phreatoicoides gracilis Sayce, 1900

11(1). (fig) Telsonic region or tail piece median lobe entire; penes extending to midline

12

Telsonic region or tail piece median lobe cleft; penes extending past midline and onto pleonite 1

14

 

12(11). (fig) Uropod protopod dorsomedial ridge not produced; male pleopod II endopod appendix masculina ventral shape of cross section of proximal half of shaft convex (flattened in cross section); antennal notch on head absent

Paramphisopus palustris (Glauert, 1924)

Uropod protopod dorsomedial ridge produced; male pleopod II endopod appendix masculina ventral shape of cross section of proximal half of shaft concave (forming an elongate trough); antennal notch on head present

13

13(12). (fig) Cervical groove on head straight; clypeal notch on head present; pleonite 5 lacking dorsal median ridge

Eophreatoicus sp. 6 (Kakadu National Park)

Cervical groove on head undulating; clypeal notch on head absent; pleonite 5 with dorsal median ridge

N. Gen. X3 (NW Kimberleys W.A.)

14(11). (fig) Basis dorsal ridge in cross section angular on pereopod V, produced and forming distinct plate on pereopod VII; eyes bulging dorsolaterally; pereopod IV sexually dimorphic

Amphisopus lintoni (Nicholls, 1926)

Basis dorsal ridge in cross section produced and forming distinct plate on pereopods V-VII; eyes fully sessile; pereopod IV not sexually dimorphic

15

15(14). (fig) Uropod protopod dorsomedial ridge not produced; antennal notch absent; dorsal uropodal ridge present

Phreatomerus latipes (Dead Woman Springs, SA)

Uropod protopod dorsomedial ridge produced; antennal notch present; dorsal uropodal ridge absent

Synamphisopus ambiguus (Sheard, 1936)

16(1). (fig) Pereopods V-VII basis dorsal ridge in cross section angular

17

Basis dorsal ridge in cross section angular on pereopod V, produced and forming distinct plate on pereopod VII

18

17(16). (fig) Eyes present; mandibular left spine row with first spine not separated from remainder of spine row; male pleopod II endopod appendix masculina proximal shaft ventrally concave (forming an elongate trough)

Colubotelson sp. (Penstock Lagoon, Tasmania)

Eyes vestigial, or absent; mandibular left spine row with first spine separated from remaining spines; male pleopod II endopod appendix masculina proximal shaft ventrally convex or rod-like

Crenoicus buntiae Wilson & Ho, 1996

18(16). (fig) Telsonic region or tail piece median lobe entire; mandibular right lacinia mobilis absent, all spines in spine row similar in position, size and shape; uropodal protopod dorsomedial ridge produced

19

Telsonic region or tail piece median lobe broadly incised; mandibular right lacinia mobilis large, well separated and distinct from spine row; uropodal protopod dorsomedial ridge not produced

New Genus X4 (Toolbrunup Peak, WA)

19(18). (fig) Penes distal tip rounded; pereopod I dactylus subequal to palm in female; pereopod I propodal palm in female stout denticulate setae present, serrate

20

Penes distal tip flattened; pereopod I dactylus shorter than palm in female; pereopod I propodal palm in female stout denticulate setae absent

Metaphreatoicus australis (Chilton, 1891)

Penes distal tip truncate; pereopod I dactylus projecting beyond palm in female; pereopod I propodal palm in female stout denticulate setae present, bifid

cf. Metaphreatoicus sp. (Thredbo River, NSW)

20(19). (fig) Clypeal notch on head present; male pleopod I exopod dorsal surface with setae; pleotelson lateral length less than depth

21

Clypeal notch on head absent; male pleopod I exopod dorsal surface lacking setae; pleotelson lateral length subequal to depth

Colubotelson searli Nicholls, 1944

21(20). (fig) Eyes fully sessile; male pleopod II endopod appendix masculina ventral shape of cross section of proximal half of shaft convex (flattened in cross section); male pleopod II endopod appendix masculina distal tip truncate

Colubotelson joyneri (Nicholls, 1926)

Eyes bulging dorsolaterally; male pleopod II endopod appendix masculina ventral shape of cross section of proximal half of shaft concave (forming an elongate trough); male pleopod II endopod appendix masculina distal tip broadly rounded

Colubotelson sp. (Uni. Tas.)

 
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