Prohydrometra tohiea 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 : 83-84

Prohydrometra tohiea D. Polhemus n. sp.

Figs. 23 , 25 , 29

Apterous male. Length 6.60, width 0.38.

Color. Ground color brown to blackish-brown; abdomen light-brown medially, matte. Head broadly tinged with blackish. Thorax anteriorly and medially light colored dorsally; abdominal mediotergites light medially; each laterotergite with light area anteriorly. Venter of thorax and abdomen dark. Legs light-brown, antennae light-brown to brown; coxae and trochanters mostly light-brown.

Structure. Head relatively long (2.43), widest at antenniferous tubercles (0.40); set with bristly setae beneath; gular lobe large, rounded; labium reaching well caudad of eyes, onto prosternum; head with anteocular portion slightly longer than postocular portion, ratio of anteocular/postocular portions: 1.38/0.95; interocular space/width of an eye: 0.08/0.10; anteclypeus small, broadly rounded anteriorly. Antennae with lengths of antennomeres I:II:III: IV = 0.40: 0.50: 2.53: 1.45.

Thorax with pronotum length 0.78; remainder of thorax 0.45 (to lateral suture behind metacetabula); abdomen length 2.70. Wing pads, if present, very small, not visible, hidden under pronotum.Thoracic and abdominal sterna with short bristly setae, about equally dense on all segments. Distance between anterior and middle coxae (measured between closest margins) 0.18; between middle and hind coxae 0.30. Acetabula without pits. Venter without black denticles.

Proportions of legs as follows: Femur, tibia, tarsomere I, tarsomere II, tarsomere III of fore-leg, 2.50: 3.10: 0.05: 0.40: 0.20; of middle-leg, 2.80: 3.50: 0.07: 0.35: 0.18; of hind-leg, 3.90: 5.80: 0.07: 0.45: 0.20.

First abdominal segment short, transverse, clearly delineated by a suture posteriorly. Mediotergites longer than wide. Male abdominal sternum VII with two elongate patches of erect bristles, widely separated, and displaced from the anterior margin ( Fig. 23 ); segment VIII cylindrical, unmodified, without distal process.

Micropterous female. Length 7.50, width across abdomen 1.40. Similar in most respects to male, including antennomere ratios, but abdomen broader; abdominal mediotergites II–VII longitudinally rectangular, tergum VIII trapezoidal, distally truncate, without distal process; margins of laterotergites without setae. Abdominal terminalia simple, without modification.

Brachypterous and macropterous forms. Unknown.

Type material examined (all micropterous). Holotype, male: FRENCH POLYNESIA, Society Islands , Moorea , small gulch immediately W. of Mt. Tohiea summit (headwaters of Mahaeru River), 1150 m, 17°33'04"S, 149°49'22"W, 12 September 2006, 10:40–15:00 hrs., CL 7500, D. A. Polhemus ( BPBM) . Paratypes: FRENCH POLYNESIA, Society Islands , Moorea , 4 males, same data as holotype, CL 7500, D. A. Polhemus ( BPBM, USNM) ; 1 female, Moorea , Mt. Tohiea, 17°33'04"S, 149°49'23"W, 1100 m, 12 September 2006, lot 04, pyrethrin fog of mossy log, J. K. Liebherr ( CUIC) ; 1 female, Moorea , Mt. Tohiea, 17°33'04"S, 149°49'23"W, 1100 m, 12 September 2006, lot 03, beating Dicranopteris ferns, J. K. Liebherr ( CUIC) .

Distribution. French Polynesia, Society Islands, endemic to the island of Moorea ( Fig. 29 ).

Etymology. The species name “ tohiea ” is a noun in apposition, and refers to the Mt. Tohiea type-locality, the highest summit on the island of Moorea.

Discussion. The male of P. tohiea differs from all other species of the genus in the modification of male abdominal ventrite VII, which possesses two widely separated, longitudinally elongated patches of bristles ( Fig. 23 ). In the other two species in the genus which possess bristle patches rather than sclerotized processes, P. teatara from Tahiti and P. johnpolhemi from Raiatea, the patches are much smaller and roughly triangular in shape (compare Figs. 22–24 ). All of these species may represent individual island representatives of a common clade within the genus, but this has yet to be definitively established.

Females of P. tohiea occur syntopically with those of P. moorea , and are quite similar in many respects, but in this sex the two species can be separated by the relative lengths of the antennomeres, with segment III being less than 6.5 times that of antennomere I in P. tohiea , versus over 7.3 times as long as antennomere I in P. moorea .

Ecological notes. The type series was taken from a small pocket of wet forest immediately below the summit of Mt. Tohiea, bordered by sheer cliffs ( Fig. 25 ). Prohydrometra tohiea occurred there in company with P. moorea , three species of locally endemic Nabidae ( Nabis toheia D. Polhemus, 2010 , N. mooreana D. Polhemus, 2010 , and N. polynesica D. Polhemus, 2010 ), and an undescribed species of arboreal Saldidae . All were taken by light pyrethrin fogging of fern banks and mossy tree trunks, or by beating banks of Dicranopteris Bernh. ferns.

Figures

FIGURE 29. Distribution of Prohydrometra n. gen. species in the eastern Society Islands. Triangle = P. tohiea n. sp.; circle = P. moorea n. sp.; squares = P. gangei; pentagon = P. teatara n. sp.

FIGURES 19–24. Prohydrometra n. gen. species, male ventral terminal abdomen. 19. P. gagnei, specimen from Tahiti, Mt. Marau. 20. P. gagnei, specimen from Tahiti, Mt. Mauru, showing yellowish-brown coloration. 21. P. moorea n. sp., specimen from Moorea, Mt. Tohiea. 22. P. teatara n. sp., specimen from Tahiti, Mts. Teatara. 23. P. tohiea n. sp., holotype, specimen from Moorea, Mt. Tohiea. 24. P. johnpolhemi n. sp., specimen from Raiatea, Trois Cascade.

FIGURES 25, 26. Photographs of habitat for Prohydrometra n. gen. species on Moorea and Tahiti. 25. Mt. Tohiea summit area, CL 7500, habitat for P. moorea n. sp. and P. tohiea n. sp.. 26. Tahiti Iti, Mts Teatara, 1080 m. mossy Weimannia trees providing habitat for P. teatara n. sp..