Prohydrometra englundi D. Polhemus, 2022

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 : 78-81

Prohydrometra englundi D. Polhemus n. sp.

Figs. 12–15 , 18

Apterous female. Length 5.55, width 0.80.

Color. Ground color yellowish-brown, body slightly darker than appendages, abdominal laterotergites with faintly suggested paler areas on anterior halves; legs and antennae uniformly pale yellowish-brown.

Structure. Head relatively long (2.00), widest at antenniferous tubercles (0.45); bearing numerous fine, erect, slightly curving setae ( Fig. 12 ); gular lobe large, rounded, covering first two labial articles in lateral view; labium reaching well caudad of eyes, onto middle of prosternum, length 2.15, head with anteocular portion slightly longer than postocular portion, ratio of anteocular/postocular portions: 1.00/0.75; interocular space/width of an eye: 0.07/0.05; anteclypeus small, broadly rounded anteriorly ( Fig. 12 ). Antennae with antennomere III very elongate, lengths of antennomeres I:II:III:IV = 0.30: 0.35: 2.15: 1.30. Pronotum length 0.75; remainder of thorax 0.50 (to lateral suture behind metacetabula); bearing numerous fine, erect, slightly curving setae. Abdomen length 2.52, bearing numerous short, semi-appressed black setae, these setae shorter and less erect than those on head and thorax; abdominal apex acute ( Fig. 14 ). Wing pads, if present, very small, not visible, hidden under pronotum. Thoracic and abdominal sterna with numerous moderately short, fine, semi-appressed setae, about equally dense on all segments. Coxal spacing unequal ( Fig. 13 ), with hind coxae posteriorly displaced, distance between anterior and middle coxae (measured between closest margins) 0.45; between middle and hind coxae 0.55. Acetabula without pits. Venter without black denticles, ventral suture between thorax and abdomen obscure.

Legs with femora thicker than tibiae ( Fig. 15 ); hind tibia very long; proportions of legs as follows: femur, tibia, tarsomere I, tarsomere II, tarsomere III of fore-leg, 1.70: 1.95: 0.05: 0.15: 0.18; of middle-leg, 1.75: 2.10: 0.05: 0.20: 0.15; of hind-leg, 2.30: 3.15: 0.05: 0.20: 0.16.

First abdominal segment short, transverse, width/length = 0.35/0.15, clearly delineated by a suture posteriorly. Mediotergites II–V nearly quadrate, all subequal in length, slightly longer than wide; abdominal mediotergites VI and VII broader than long; abdominal apex pointed.

Male, brachypterous form and macropterous form: Unknown.

Type material examined ( all micropterous). Holotype, female: FRENCH POLYNESIA, Society Islands , Raiatea , Mt. Toomaru summit area, 800 m, 16.8221 S, 151.4547 W, 7 February 2006, taken by pyrethrin fog of mossy Metrosideros collina trunk, R. Englund ( BPBM). FRENCH POLYNESIA, Society Islands, Raiatea, 1 female, same data as holotype, ( BPBM).

Distribution. French Polynesia, Society Islands, endemic to the island of Raiatea ( Fig. 18 ).

Etymology. Named for Dr. Ron Englund, a stalwart colleague in the field, who collected the only two known specimens.

Discussion. Females of Prohydrometra species are for the most part quite similar, and therefore not suitable for species diagnosis. In the case of P. englundi , however, the presence of numerous long, fine, erect setae on the head and thorax ( Figs. 12, 13 ), which are similar to the character state seen in Chaetometra robusta from the Marquesas, allow easy recognition of this taxon, despite the fact that only two females are in hand. This character state is unique among the currently known species placed in Prohydrometra .

Although it was initially considered that P. englundi might be another geographically disjunct species of Chaetometra , due to the long setae on the body, the length of the head ( Fig. 12 ), the very long and diagnostic antennomere III, and the slightly unequal coxal spacing ( Fig. 13 ) all indicate a placement in Prohydrometra . In addition, the legs of P. engundi are far more slender, and lack the numerous long, erect pilose setae seen in Chaetometra ( Figs. 35, 36 ).

Ecological notes. The type series was taken by localized pyrethrin fogging of moss mats covering the trunk of a Metrosideros collina tree in the Mt. Toomaru summit area of Raiatea.

Figures

FIGURE 18. Distribution of Prohydrometra species in the western Society Islands. Triangle = P. johnpolhemi n. sp.; square = P. englundi n. sp.

FIGURES 12–15. Prohydrometra englundi n. sp., female, morphological details. 12. Head, dorsal view, with positions of cephalic trichobothria indicated. 13. Ventral left thorax, showing coxal spacing. 14. Terminal abdomen, ventral view. 15. Left foreleg, ventral view. Specimen from French Polynesia, Raiatea, Mt. Toomaru.

FIGURES 35–37. Chaetometra robusta, holotype, structural details. 35. Lateral view. 36. Dorsal view. 37. Head.