Rhagovelia dibuwa, Polhemus, 2024

Polhemus, Dan A., 2024, Thirty-four new species of Rhagovelia (Heteroptera: Veliidae) from the East Papua Composite Terrane, far eastern New Guinea, Zootaxa 5400 (1), pp. 1-214 : 55

Rhagovelia dibuwa subgroup

The R. dibuwa subgroup is a set of moderate to large-sized species within the context of the R. novacaledonica group, with body lengths ranging from 3.5–4.8 mm. Most of these species are predominantly dark colored, with limited dark yellow or orange-brown markings on the anterior pronotum and connexiva ( Figs. 85, 86 , 92, 93 , 99, 100 , 106, 107 , 118, 119 , 125, 126 ), but in a few taxa from the D'Entrecasteaux Islands there is marked intraspecific color polymorphism, with both dark grey and orange-brown forms present ( Figs. 107, 109 ). Males have connexival margins that are gently sinuate, being bowed slightly inward along their central sections, whereas in females the connexival margins are uniformly straight, converging evenly toward the posterior margin of the abdomen but not touching at their apices, and thus leaving all of the abdominal tergites exposed in dorsal view ( Figs. 86 , 93 , 100 , 107 , 119 , 126 ). The male pregenital segment (VIII) is comparatively elongate, and bears a transverse sulcus basally, causing it to appear constricted in lateral view. The male paramere has a distinctive shape, with a relatively straight ventral margin, and an expanded distal section that forms an upward-angling lobe ( Figs. 89 , 96 , 103 , 114 , 122 , 129 ). The male proctiger has the distolateral lobes only modestly developed at best, whereas the basolateral lobes are strongly developed and in some cases diagnostic for species separation ( Figs. 90 , 97 , 104 , 115 , 123 , 130 ). Female abdominal tergites V–VIII may bear shining patches centrally, the presence or absence of which on a particular tergite may also be useful for species separation. The prosternum and jugae lack black denticles.

The R. dibuwa subgroup contains six morphologically similar species— R. watuti , R. peninsularis , R. kalawai , R. dibuwa , R. awaetowa and R. torrenticola —occurring in the mountain ranges at the far eastern extremity of the Papuan Peninsula, and on the adjacent offshore islands, including those of the D’Entrecasteaux Islands and others lying immediately east of the China Strait. These species are found on rocky upland streams ( Figs. 91 , 98 , 105 , 116 , 117 , 124 , 131 ), being most typically encountered at elevations above 100 m.

The D'Entrecasteaux group is a geologically young archipelago that has only formed in the past 5 my ( Abers et al. 2002) and as such, speciation there has of necessity been relatively recent, a pattern also seen in recent studies of microhylid frogs occurring in the archipelago ( Hill et al., 2023). The species in the R. dibuwa subgroup that occur there possess many common morphological character states, a situation also repeated in the R. loriae subgroup of the R. papuensis group, which occurs across this same geography, and often intermixes with members of the R. dibuwa subgroup on the same streams (see subsequent discussion under that subgroup). Even so, these insular Rhagovelia populations are currently allopatric, being separated by deep water barriers that persisted throughout the Pleistocene, and the differences between the island populations are sufficient to consider them separate species in the context of the current monograph. It seems possible that these insular species originated from an ancestral stock present along the southern side of the Papuan Peninsula, since there are potential homologies in certain character systems to morphologically similar taxa occurring in that area, such as R. mimani . Counterintuitively, the R. novacaledonica group species occurring on the north side of the Papuan Peninsula, in closer proximity to the D’Entrecasteaux Islands, share fewer potentially homologous character states and seem more distantly related.

Figures

FIGS. 85–90. Rhagovelia watuti n. sp., structural details; specimens from New Guinea, Cloudy Mountains, CL 7175. 85. Wingless male, dorsal habitus. 86. Wingless female, dorsal habitus. 87. Male right hind leg, posterior view. 88. Male right hind leg, dorsal view. 89. Male left paramere, outer lateral view. 90. Male proctiger, dorsal view.

FIGS. 92–97. Rhagovelia peninsularis n. sp., structural details; specimens from New Guinea, Alotau area, CL 7163. 92. Wingless male, dorsal habitus. 93. Wingless female, dorsal habitus. 94. Male right hind leg, posterior view. 95. Male right hind leg, dorsal view. 96. Male left paramere, outer lateral view. 97. Male proctiger, dorsal view.

FIGS. 99–104. Rhagovelia kalawai n. sp., structural details; specimens from Sideia and Basilaki islands. 99. Wingless male, dorsal habitus, Basilaki Island, CL 7294. 100. Wingless female, dorsal habitus, Sideia Island, CL 7287. 101. Male right hind leg, posterior view. 102. Male right hind leg, dorsal view. 103. Male left paramere, outer lateral view. 104. Male proctiger, dorsal view; 101–104 all from Basilaki Island, CL 7294.

FIGS. 106–109. Rhagovelia dibuwa n. sp., dorsal habitus photos, specimens from Normanby Island. 106. Wingless male, dark form, dorsal habitus. 107. Wingless female, dark form, dorsal habitus; 108. Winged male, dark form, dorsal habitus; 106–108 all from Bunama, Apatabuia River, CL 7228. 109. Wingless female, orange-brown form, dorsal habitus, specimen from Dibuwa River, CL 7230.

FIGS. 118–123. Rhagovelia awaetowa n. sp., structural details; specimens from Fergusson Island. 118. Wingless male, dorsal habitus. 119. Wingless female, dorsal habitus. 120. Male right hind leg, posterior view. 121. Male right hind leg, dorsal view; 118–121 from upper Awaetowa River, CL 7225. 122. Male left paramere, outer lateral view. 123. Male proctiger, dorsal view; 122 and 123 from lower Awaetowa River, CL 7183.

FIGS. 125–130. Rhagovelia torrenticola n. sp., structural details; specimens from Goodenough Island. 125. Wingless male, dorsal habitus, specimen from Yalaauau, CL 7186. 126. Wingless female, dorsal habitus, specimen from Tuabeda River at Kalauna, CL 7184. 127. Male right hind leg, posterior view. 128. Male right hind leg, dorsal view; 127 and 128 from Yalaauau, CL 7186. 129. Male left paramere, outer lateral view. 130. Male proctiger, dorsal view; 129 and 130 from Tuabeda River at Kalauna, CL 7184.

FIGS. 110–115. Rhagovelia dibuwa n. sp., structural details; specimens from Normanby Island. 110. Male right hind leg, weakly developed individual, posterior view. 111. Male right hind leg, weakly developed individual, dorsal view. 112. Male right hind leg, strongly developed individual, posterior view. 113. Male right hind leg, strongly developed individual, dorsal view; 110–113 from Dibuwa River, CL 7230. 114. Male left paramere, outer lateral view. 115 Male proctiger, dorsal view; 114 and 115 from Bunama, Apatabuia River, CL 7228.

FIG. 91. Watuti River headwaters, Cloudy Mountains, Milne Bay Province, Papua New Guinea, CL 7175, type-locality for R. watuti n. sp.

FIG. 98. Goilayoli River headwaters, east of Alotau, Milne Bay Province, Papua New Guinea, CL 7161, habitat for R. peninsularis n. sp.

FIG. 105. Kalawai River, Basilaki Is., Milne Bay Province, Papua New Guinea, CL 7294, type-locality for R. kalawai n. sp.

FIG. 116. Apatabuia River above Bunama, Normanby Is., Milne Bay Province, Papua New Guinea, CL 7228, type-locality for R. dibuwa n. sp.

FIG. 117. Tributary to the upper Dibuwa River, Normanby Is., Milne Bay Province, Papua New Guinea, CL 7230, habitat for the orange-brown form of R. dibuwa n. sp.

FIG. 124. Awaetowa River headwaters, Fergusson Is., Milne Bay Province, Papua New Guinea, CL 7225, type-locality for R. awaetowa n. sp.

FIG. 131. Tuabeda River above Kalauna village, Goodenough Is., Milne Bay Province, Papua New Guinea, CL 7184, typelocality for R. torrenticola n. sp.