Dolichocephalametra pacifica ( Van Duzee, 1934 )

Polhemus, Dan A., 2022, Two new genera and six new species of Terrestrial Hydrometridae (Hemiptera: Heteroptera) from French Polynesia, Zootaxa 5190 (1), pp. 69-98 : 90

Dolichocephalametra pacifica ( Van Duzee, 1934)

Figs. 30–34

Hydrometra pacifica Van Duzee, 1934: 326 [date on publication cover indicates 1935, but a footnote to the article states publication on 10 July 1934].

Dolichocephalometra pacifica: Hungerford, 1939: 219 .

Discussion. The extremely elongate head with reduced eyes ( Fig. 32 ) will immediately distinguish this taxon from any other in Hydrometridae . The original description by Van Duzee (1934) stated that the male holotype, which is housed in the Bishop Museum, was also accompanied by a male paratype, but this latter specimen is not present in the Bishop Museum collection. Hungerford (1939) noted that he had examined this paratype, and it is possible that it may still be retained in the collection at the University of Kansas. Photographs of the holotype are provided here to aid in future recognition of this extremely aberrant species ( Figs. 30–32 ).

Ecological notes. Dolichocephalometra pacifica was described based on two male specimens taken in 1931 on Mt. Hitikau, the highest summit on the small island of Ua Huka, in the Marquesas ( Van Duzee, 1934). No specimens have been seen since, so an effort was made on 2 November 1999 to revist the type-locality in search of additional examples. Cloud forest on Ua Huka is confined to the eastern portion of the island's central ridge, lying around 900 m elevation, and the name Hitikau means “the mountain where one goes up by swimming through vegetation.” This appellation is appropriate, in that Hitikau was the only summit sampled in the Marquesas which lacked mossy, emergent trees, being covered instead with a rather uniform mixture of low stature Hibiscus tiliaceus (L.) Fryxell and Freycinetia arborea ( Fig. 33 ), with an understory of ferns, matching a previous description provided by Adamson (1936). A few moist, protected sites on the slopes also supported tree ferns and broad-leafed shrubs. Moss began to cover the Hibiscus branches on the upper 100 meters of the mountain, but the pads were not dense, and many were dry to the touch, despite the misty weather. Collecting for Heteroptera here was poor, and no additional specimens of D. pacific a were obtained, but the visit was sufficient to confirm that no aquatic habitat is present at the typelocality, and that this species is almost certainly terrestrial.

Distribution. French Polynesia, Marquesas Islands, Ua Huka ( Fig. 34 ).

Material examined. FRENCH POLYNESIA, Marquesas Islands, Ua Huka: 1 female, Hitikau , 2900 ft., on ferns 20 January 1932, leg. LeBronnec and H. Tauraa (holotype, BPBM) .

Figures

FIGURE 33. Photograph of the type-locality for Dolichocephalometra pacifica, the summit ridge of Mt. Hitikau, Ua Huka, Marquesas Islands. Note the thick stand of Freycinetia arborea in which the survey crew is sheltering, with a few slender Hibiscus tiliaceus in the left of the frame.

FIGURE 34. Distribution of Dolichocephalometra pacifica in the northern Marquesas Islands.

FIGURES 30–32. Dolichocephalometra pacifica, holotype, structural details. 30. Lateral view. 31. Dorsal view. 32. Head.