Prohydrometra D. Polhemus 2022, n. gen.
Creators: name: Polhemus, Dan A.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hemiptera
Hydrometridae
Prohydrometra

description: Prohydrometra D. Polhemus n. gen.
Figs. 9–29
Description. Body small for family, narrow (see J. Polhemus & D. Polhemus 1995a, Fig 1); body without black spicules; body lengths 4.15–7.20.
Color: Ground blackish-brown to yellowish-brown; legs slightly paler; abdominal laterotergites often with faintly suggested paler areas on anterior halves.
Structural characters: Head relatively long, anteocular portion slightly longer than postocular portion (Figs. 10, 12), ratio varying from 1.33/1.00 to 1.59/1.00; eyes small, with dorsal eye width subequal to or less than width of interocular space (Figs. 10, 12); labium long, reaching onto prosternum; antennae long, combined length equal to nearly that of body, slender, antennomere II longer than antennomere I, antennomere III over 5 times as long as antennomere II (Fig. 11), antennomere IV about 3 times as long as antennomere II.
Thorax widened posteriorly; pronotal lobe short, extending posteriorly over mesonotum, metanotum exposed, without any trace of wing pads; acetabula without pits.
Legs slender, moderately long, combined lengths of hind leg segments about 1.3 times as long as body; foreto-middle versus middle-to-hind coxal spacing unequal, ratio varying from 1.00/1.22 to 1.00/1.90 (Figs. 9, 13); pretarsus with both dorsal and ventral arcuate arolia, parempodia long, setae-like.
Abdomen with segment I clearly delineated, short, rectangular; abdominal mediotergites II–VII rectangular, slightly longer than wide, length to width ratio about 1.1/1.0; female abdominal sternum VII and tergum VIII without caudal processes; male abdominal sternum VII bearing paired sclerotized processes or modified setal patches to either side of longitudinal midline (Figs. 19–24).
Type-species. Hydrometra gagnei J. Polhemus & D. Polhemus, 1995a.
Etymology. The generic name Prohydrometra is derived from pro-, L., before, and Hydrometra, water measurer. Gender feminine.
Distribution. French Polynesia, Society Islands (Moorea, Raiatea, Tahiti).
Discussion. Prohydrometra possesses a set of character states that are intermediate between the putatively plesiomorphic conditions seen in Marquesametra, and the more modified states seen in Hydrometra. The abdomen is longer than in Marquesametra, in which the mediotergites are quadrate and equilateral, but shorter than in Hydrometra, with abdominal mediotergites III–VI weakly rectangular, being slightly longer than wide, but not nearly so elongate as in Hydrometra. The hind coxae are slightly more posteriorly displaced to varying degrees compared to the condition seen in Marquesametra, where the spacing is nearly equal (compare Figs. 3, 9, 13), but still far less asymmetrical than the condition seen in Hydrometra. The legs are longer longer than in Marquesametra, with the combined length of the hind leg slightly longer than the body, but shorter and less thread-like than in Hydrometra species. Similar to Marquesametra, but in contrast to Hydrometra, the body lacks both black spicules ventrally, and pits on the acetabula. The posterior pair of cephalic trichobothria is set on low tubercles, similar to Hydrometra species and the three endemic Marquesan genera, and the eyes are somewhat reduced, a character state also prevailing in the endemic Marquesan genera. This suite of characters, as well as those discussed previously under Marquesametra, serve to separate this genus from others in the family. In addition, the members of this genus have a diagnostic antennal morphology, with the combined lengths of the antennomeres being subequal to that of the body, due to a highly elongated antennomere III, which is five times the length of antennomere II (Fig. 11).
description: Published as part of Polhemus, Dan A., 2022, Two new genera and six new species of Terrestrial Hydrometridae (Hemiptera: Heteroptera) from French Polynesia, pp. 69-98 in Zootaxa 5190 (1) on page 76, DOI: 10.11646/zootaxa.5190.1.3, http://zenodo.org/record/7119849