Cladistics of Hygrobia

Name

• Hygrobia Latreille, 1804

Fig. 1: Hygrobia hermanni, head

Fig. 2: Hygrobia maculata, head

This page summarizes morphological characters which we used for a cladistic analysis of Hygrobia. This page is work in progress, and we encourage colleagues to participate and make this the first interactive cladistic wiki analysis. The main goal of this project was to test if Hygrobia davidi can be placed based on morphological characters, so that the topology of a molecular phylogeny of all other species can be interpreted more soundly. Hygrobia davidi was described from SE China, based on a single historical male specimen, and never collected again. It occurs right in the middle between the other two major extant distributional areas of Hygrobia - the West Palearctic and Australia.

Head

• ► Char. 1 Clypeal suture (Figs 1a, 2a): faint (H. maculata, H. wattsi) to almost invisible (other Australian species) (0), well visible, strongly impressed (1).
• ► Char. 2 Clypeus, shape (Figs 1b, 2b): anterior angles not significantly produced forward (0), anterior angles produced forward into a triangular extension (1).
• ► Char. 3 Labrum, shape (Figs 1c, 2c): foremargin straight (0), foremargin concave (1).
• ► Char. 4 Labrum, surface (Figs 1c, 2c): smooth (0), with large, coarse punctures (1), with dense, but not coarse puncturation.

Pronotum

• ► Char. 5 Hind margin in dorsal (!) view rather straight (0); hind margin curved on both sides (1), triangular in the middle (2).

Protarsus ♂ (Figs 3, 4)

• ► Char. 6 Tarsomeres 1–3: not dilated, ventrally only with short setae (0); sligthly dilated, ventrally with long adhesive setae (1); more strongly dilated, ventrally with long adhesive setae (2).
• ► Char. 7 Claws: longish, curved (0); shorter, strongly curved (1).

Additional characters from Beutel et al. 2006

• ► Char. 8 Compound eyes undivided (0), divided (1) (Char 3 in Beutel et al. 2006).

• ► Char. 9 Shape of scapus: (0) other (1) strongly shortened but cylindrical,

without enlarged globular part (Char 8 in Beutel et al. 2006).

• ► Char. 10 Origin of metafurca: (0) katepisternum; (1) intercoxal

septum (Char. 61 in Beutel et al. 2006).

• ► Char. 11 Mesal walls of metacoxa: (0) other (1)

connected, contact area extensive, intercoxal septum (Char 66 in Beutel et al. 2006).

• ► Char. 12 Lateral margin of metacoxal plates: (0) other (1) slightly

diverging anteriorly (Char. 70 in Beutel et al. 2006).

• ► Char. 13 Pedicellus: (1) strongly shortened and largely enclosed by

distal part of scapus, (0) other (Char. 9 in Beutel et al. 2006).

• ► Char. 14 Body shape: (1) pronoto-elytral angle present,

distinct (120 degress or less); (0) other (Char. 1 in Beutel et al. 2006).

• ► Char. 15 Large epipharyngeal sensilla: (1) absent; (0) present (Char. 7 in Beutel et al. 2006).

Character Matrix

Species / ► Character	►1	►2	►3	►4	►5	►6	►7	►8	►9	►10	►11	►12	►13	►14	►15
hermanni	1	1	1	1	0	2	1	0	0	1	1	1	0	0	1
davidi	1	1	0	1	0	2	0	0	0	1	1	1	0	0	1
australasiae	0	0	0	0	1	1	0	0	0	1	1	1	0	0	1
maculata	0	0	0	0	1	1	0	0	0	1	1	1	0	0	1
nigra	0	0	0	0	1	?	?	0	0	1	1	1	0	0	1
wattsi	0	0	0	0	1	0	0	0	0	1	1	1	0	0	1
Amphizoa lecontei	0	0	1	1	0	0	0	0	0	1	1	1	0	1	0
Aspidytes niobe	0	0	1	0	0	0	2	0	0	1	1	1	1	0	0
Peltodytes dispersus	0	0	0	0	2	0	0	0	1	0	0	0	0	0	0
Dineutus ciliatus	1	0	0	2	0	0	1	1	0	0	0	0	0	0	0

Fig. 5: Parsimony tree for Hygrobia, with jackknife values (1000 pseudoreplications, 36% deletion)

Fig. 3: Hygrobia hermanni

Fig. 4: Hygrobia australasiae

Reference

Beutel. R.G., Balke, M. & Steiner Jr., W.J. 2006. The systematic position of Meruidae (Coleoptera, Adephaga) based on a cladistic analysis of morphological characters. Cladistics 22, 102–131.