Marquesametra hivaoa 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 : 72-76

Marquesametra hivaoa D. Polhemus , n. sp.

Figs. 1–8 , 38

Micropterous male. Length 3.90–4.30, width 0.40–0.50.

Color: Ground color brown; abdominal mediotergites light brown, matte. Head tinged with blackish ventrally, and dorsally anterad of eyes. Thorax dorsally with narrow median longitudinal frosted stripe, pronotum laterally with narrow frosted longitudinal stripe; each laterotergite with frosted area anteriorly. Venter of thorax and abdomen dark. Legs light brown to brown, darker distally, antennae brown to dark brown; coxae and trochanters mostly light brown, similar to bases of femora.

Structural characters: Head ( Fig. 2 ) relatively long (1.55), widest at antennal tubercles (0.32); set with bristly setae beneath; gular lobe large, rounded; labium reaching well caudad of eyes, onto prosternum; ratio of anteocular/ postocular portions: 0.47/0.54; interocular space/width of an eye: 0.11/0.05; anteclypeus small, broadly rounded anteriorly ( Fig. 1 ). Antennal formula I:II:III:IV; 0.23: 0.29: 1.04: 0.86. Entire body covered with very small shallow frosted foveae.

Pronotum length 0.61; remainder of thorax 0.25 (to lateral suture behind metacetabula); abdomen length 1.87. 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 centers) 0.35; between middle and hind coxae 0.42 ( Fig. 3 ); acetabula without pits. Venter without black denticles.

Legs with proportions as follows: femur, tibia, tarsomere I, tarsomere II, tarsomere III of fore-leg, 1.15: 1.30: 0.05: 0.16: 0.11; of middle-leg, 1.19: 1.37: 0.05: 0.18: 0.14; of hind-leg, 1.62: 2.23: 0.05: 0.23: 0.18.

Abdomen with first segment short, transverse, clearly delineated by a suture posteriorly. Male abdominal terminalia as shown in Fig. 4 , segment VIII cylindrical, unmodified, without distal process. Sternum VII without modifications.

Micropterous female. Length 4.61, width across abdomen 0.83. Similar in most respects to male, but abdomen broader, deeper, mediotergite VIII distally truncate, without distal process; margins of laterotergites lacking setae.

Brachypterous and macropterous forms. Unknown.

Type material examined (all micropterous). Holotype, male: FRENCH POLYNESIA, Marquesas Islands, Hiva Oa, Mt. Temetiu , high point on ridge to S. of trail crest, 1190 m, 9°48'02" S, 139°04'41" W, 14 August 2001, ex. pyrethrin fogging of thick moss on Metrosideros collina, CL 6031b, D. A. Polhemus & R . Englund ( BPBM) . Paratypes: FRENCH POLYNESIA, Marquesas Islands, Hiva Oa : 6 males, 2 females, same data as holotype ( USNM, BPBM); 1 male, 1 female, Temetieu Ridge, pyrethrin fog of thick moss on large Metrosideros collina tree at ridge crest, 1112 m, 9°47'54"S, 139°04'44"W, 26 October 1999, CL 6016, D. A. Polhemus, J. T . Polhemus, R . Englund and S. Jordan ( USNM); 4 males, Temetieu Ridge , pyrethrin fog of thick moss on Metrosideros collina trees near camp on ridge crest, 1095 m, 9°47'56" S, 139°04'45" W, 14 August 2001, CL 6031a, D. A. Polhemus, R . Englund and S. Jordan ( USNM, BPBM) .

Distribution. Known only from the island of Hiva Oa in the Marquesas Islands ( Fig. 38 ).

Etymology. The species name is a noun in apposition, and refers to the Hiva Oa island type-locality.

Discussion. Marquesametra hivaoa may be separated from the the other two endemic species of Hydrometridae previously described from the Marquesas by the characters provided in the key to genera, and covered in the previous discussion under the new genus description. As noted there, in certain respects Marquesametra hivaoa resembles species of Prohydrometra occurring on the Society Islands, suggesting that these species may have arisen from a common lineage that colonized the insular Pacific at some time in the past, but they differ in several important character states related to the form of the antennae, coxal spacing, and ventral abdominal structure.

Ecological notes. The type-material of M. hivaoa was taken from the summit ridge of Mt. Temetiu, the highest mountain on the island of Hiva Oa. This area lacked any aquatic habitats, being covered with wet cloud forest vegetation ( Figs. 5–8 ) consisting of large, isolated, moss-covered Metrosideros collina trees lying in the lee of the ridge crest, but not forming a closed canopy. The intervening understory vegetation was dense, consisting largely of the climbing pandanus, Freycinetia arborea Gaudich. , and many species of ferns, including scattered tree ferns. Damage from feral pigs was evident here, and had reportedly become more pronounced over the 10 years previous to our surveys, with grasses beginning to invade certain open areas created by their disturbance. Individuals of M. hivaoa were obtained here by applying a light pyrethrin fog to the dense pads of moss covering the Metrosideros trunks and branches, with sheets placed below to catch the dropping insects. By contrast, no examples of M. hivaoa were taken by beating or sweeping, demonstrating how this species can be easily missed by such conventional collecting techniques. Alhough Chaetometra robusta ( Hungerford, 1939) was described from the same ridge on Hiva Oa island, and the two taxa would thus appear to be potentially syntopic, it would seem that they must occupy different habitats, since multiple days of collecting in this area by four entomologists using a variety of techniques produced 15 specimens of Marquesametra , but no specimens of Chaetometra .

Figures

FIGURE 1. Marquesametra hivaoa n. sp., dorsal habitus. Specimen from Marquesas Islands, Hiva Oa, Mt. Temetiu, CL 6031. Young Sohn illustration.

FIGURES 2–4. Marquesametra hivaoa n. sp., morphological details. 2. Male head, dorsal view, with positions of trichobothria indicated. 3. Male ventral right thorax, showing nearly equidistant coxal spacing. 4. Male ventral terminal abdomen. Specimen from French Polynesia, Hiva Oa, Mt. Temetiu, CL 6031.

FIGURES 5–8. Photographs of habitat for Marquesametra hivaoa n. sp. on Mt. Temetiu, Hiva Oa, Marquesas Islands, CL 6016 and CL 6031. 5. View of the Mt. Temetiu summit ridge in 2001, with survey camp visible as a blue tarp shelter to the center right of the frame, at an elevation of approximately 1100 m, CL 6031. 6. Dense cloud forest vegetation along the Mt. Temetiu summit ridge, including ferns, Freycineta arborea, and moss-draped Metrosideros collina trees in the upper portion of the frame, the latter supporting M. hivaoa. 7. Dr. J. T. Polhemus applying pyrethrin fog to a mossy tree in search of M. hivaoa. 8. Detail of moss and fern habitat on Mt. Temetiu harboring M. hivaoa.

FIGURE 38. Distribution of endemic Hydrometridae species in the southen Marquesas Islands. Circles = Marquesametra hiavoa n. sp.; square = Chaetometra robusta.