Phelea breviceps Hansen, 1999

Fikáček, Martin & Watts, Chris H. S., 2015, Notes on the Australian Anacaenini (Coleoptera: Hydrophilidae): description of male of Phelea breviceps Hansen and unravelling the identity of Crenitis neogallica Gentili, Zootaxa 3980 (3), pp. 427-434 : 428-430

Phelea breviceps Hansen, 1999

( Figs. 1–20 )

Phelea breviceps Hansen, 1999a: 128 .

Phelea breviceps: Hansen (1999b: 118, catalogue) , Watts (2002: 93, notes on morphology and biology), Komarek & Beutel (2007: 221, phylogenetic analysis confirming assignment to the Anacaenini ).

Type locality. Australia, Tasmania, northern side of Cradle Mt., ca. 1370 m a.s.l. [ca. 41°40.8ʹS 145°57.0ʹE].

Type material examined. Holotype: female ( MCZ): “N. side of CradleMtTas / c4500ʹ Feb57 / Darlingtons // HOLOTYPE / Phelea breviceps / M. Hansen [red label, handwritten] // MCZ TYPE / 35208 [red label, partly handwritten] // Aug–Dec 2005 / MCZ Image / Database”.

Additional material examined. AUSTRALIA: Tasmania: 1 male ( BMNH): “N. W. Tasmania / Cradle Valley / 3000 feet / 27.i.1923 // Brit. Mus. / 1925–220 [GPS coordinates probably ca. 41°38.5ʹS 145°57.5ʹE]”; 8 females, 1 male, 2 unsexed specimens ( SAMA): western side of Cradle Mt., i.1959, in a shallow pond/tarn beside the overland track, 41°42′36″ S 145°56′ 16″E, leg. C.H.S. Watts.

Complementary description (only taxonomically/phylogenetically important characters not mentioned by Hansen (1999a) listed here): Head subquadrate in dorsal view, clypeus arcuately excised when seen in frontodorsal or frontal views ( Figs. 1, 5 ); labrum large, strongly sclerotized, deflexed into a vertical position and hence well visible in frontal view only ( Figs. 1, 2, 5 , 7–8 ), bearing a transverse row of setae dorsally along anterior margin ( Fig. 8 ); apical maxillary palpomere with a few digitiform sensilla on dorsoposterior face ( Fig. 11 ); trichobothria present on clypeus, frons and pronotum (not examined on elytra), basal socket large but ca. of the size of surrounding punctation and hence not distinguishable from it under binocular microscope, hairs of trichobotria moderately long and rather stout ( Fig. 9, 13 ); lateral glabrous portion of prothoracic hypomeron very wide, defined from pubescent portion by a ridge anteriorly ( Figs. 3 , 12 ); mesoventrite without distinct median posterior bulge and anterior pits or ridges ( Figs. 3 , 17, 19 ); mesofurca with short arms, dorsal projection connecting them with dorsal body wall absent; aedeagus ( Fig. 4 ) 0.7 mm long, weakly sclerotized, phallobase long and wide, with large and wide, but distinctly detached manubrium, parameres distinctly shorter than the main part of phallobase (i.e. not considering manubrium), weakly sinuate on outer margin, angulate on inner margin apically, bearing numerous pore-like sensilla on the whole surface, median lobe much longer than parameres, slightly longer than main part of phallobase, gradually narrowing towards apex, with apical gonopore and basal struts slightly longer than body of median lobe.

Diagnosis. Phelea breviceps is easy-to-recognize from other hydrophilid genera by the uniformly dark dorsal coloration (it is frequently even darker than in the illustrated specimen), rather compressed body, quadrate head with large fully sclerotized labrum which is deflexed and hence fully seen in frontal view only, mesoventrite nearly flat, without median projection, and by the unique pattern of abdominal pubescence (pubescence covering basal 2.5 ventrites, its posterior limit forms a bisinuate pattern on ventrite 3, and ventrites 4 and 5 are bare, just with few spine-like setae posteriorly; Figs. 3 , 20 ).

Distribution and biology. The species seems to be extremely restricted in distribution, as all known specimens were collected in close vicinity to Cradle Mt. in the western part of the mountain range in central Tasmania between ca. 900 and 1300 m a. s. l. ( Fig. 6 ). Collecting circumstances are unknown for the holotype and the additional specimen from BMNH. Last known record of the species is from 1959 when a short series of that species was collected by the second author from small tarns on the plateau at the base of Cradle Mt. This may prove that the species is aquatic. On the other hand, the partly reduced ventral hydrophobic pubescence (absent in metafemora and part of abdominal ventrites, Figs. 3 , 14 , 20 ) may indicate that the species may be hygropetric, i.e. inhabiting wet places but normally not submerged underwater (e.g. in the similar way as in anacaenine genera Pseudorygmodus and Horelophus , see Fikáček et al. 2012 and Fikáček & Vondráček 2014). No specimens were collected after 1959, despite the efforts of C. Watts and L. Hendrich in similar habitats across Tasmania (but the 1959 collecting site was never re-visited as it is not easy to access).

Comments on the phylogenetic position. Phelea was assigned to the Anacaenini in its original description by Hansen (1999a) and later confirmed as a member of the tribe by Komarek & Beutel (2007) who considered it as a member of the basal anacaenine stock together with Crenitis . For this study we examined the external morphology and genitalia, studies on the structure of the mouthparts or the use of DNA were impossible due to a limited number of old specimens available. The absence of long mesofurca definitely excludes Phelea from a position within any group of the Hydrophilinae . Within the remaining hydrophilid groups, the absence of the scutellary stria and the presence of digitiform sensilla on the apical maxillary palpomere indicates the position within the subfamily Chaetarthriinae, and the absence of an abdominal fringe of setae excludes assignment to the Chaetarthriini (see the discussion in Fikáček & Vondráček 2014 for details). Phelea also agrees with most anacaenine genera in the presence of a transverse row of setae on the labrum (character 11 in Komarek & Beutel 2007, overlooked for Phelea by the authors but actually present in this genus, see Fig. 8 ). The assignment to the Anacaenini hence seems well justified. Within Anacaenini , Phelea strongly resembles some members of Crenitis s.str. in the general body shape, large deflexed labrum, wide mentum with nearly straight anterior margin, pronotum with bisinuate posterior margin and lateral impressions (present in some Crenitis only, Komarek & Beutel 2007), absence of the accessory ridge below posterior margin of pronotum, wide horizontal epipleura ( Fig. 18 ), the shape of the mesoventrite (with only slightly sinuate anapleural sutures meeting together at anterior margin of mesothorax), more-or-less cylindrical metatibiae and a large manubrium on the phallobase (see e.g. Ji & Komarek 2003). Some of these characters are also shared with the New Zealand endemic Horelophus which, moreover, has a very similar morphology of the aedeagus (with wide but short parameres and very long phallobase, see Fikáček et al. 2012). Horelophus also agrees with Phelea completely in wing venation (compare drawings in Hansen (1999a) and Fikáček et al. (2012)) and shares with Phelea the presence of short club-like setae arising from dorsal punctures. On the other hand, Phelea does not seem to have modified setae on the male pro- and mesotarsi ( Figs. 15–16 ) which are present in male Horelophus . Nevertheless, it seems justified to consider Phelea tentatively as a member of the Horelophus - Crenitis clade of the Anacaenini . Thanks to its autapomorphies (quadrate head, limited pubescence of the abdomen) and the morphology of mesoventrite (flat, without transverse ridge), Phelea is easily recognizable from Crenitis . Additional effort is however needed to understand its phylogenetic position and the relationship to Crenitis .

Figures

FIGURES 1 – 6. Morphology and distribution of Phelea breviceps Hansen, 1999. 1 – 2: habitus in dorsal and lateral view, 3: ventral morphology, 4: aedeagus, 5: detail of head in frontal view, 6: known distribution in Tasmania.

FIGURES 7 – 16. Morphology of Phelea breviceps Hansen, 1999, SEM micrographs. 1 – 3: head (1: dorsal view, 2: ventral view, 3: detail of frons with trichobothria). 10 – 11: maxillary palpus (10: ventral view, 11: detail of palpomere 4 in posterodorsal view). 12 – 13: prothorax (12: ventral view, 13: detail of anterior corner of pronotum with trichobothria). 14: metafemur in ventral view. 15 – 16: mesotarsus (15: dorsal view, 16: ventral view).

FIGURES 17 – 20. Morphology of Phelea breviceps Hansen, 1999. 17: detail of mesothorax in ventral view, 18: epipleuron at level of meso-metathorax, 19: general view of meso- and metathorax in ventral view, 20: abdominal ventrites.