Porrorhynchus Laporte, 1835

Gustafson, Grey T. & Miller, Kelly B., 1835, Revision of the Southeast Asian Whirligig Beetle GenusPorrorhynchusLaporte, 1835 (Coleoptera: Gyrinidae: Gyrininae: Dineutini), The Coleopterists Bulletin 1835 (4), pp. 675-714 : 675-714

Subgenus Porrorhynchus Laporte, 1835

Trigonocheilus Dejean 1833: 59 [unavailable generic name, synonymy by Aubé, 1838a: 406].

Trigonochilus Agassiz 1846: 377 [unjustified emendation of Trigonocheilus , unavailable generic name], 1848: 1088 [unjustified emendation of Trigonocheilus , unavailable generic name].

Porrhorhynchus: Régimbart 1877a: 33 [misspelling].

Porrhorrhynchus: Régimbart 1886b: 250 [misspelling].

Dineutus (Porrorhynchus) : Ochs 1926: 64 [description].

Porrorhynchus (Ceylorhynchus) Brinck 1955: 103 . New synonymy.

Type Species. Same as for genus. Type species of Ceylorhynchus: Dineutes indicans Walker, 1858 .

Diagnosis. Large to very large whirligig beetles, size 12–26 mm. Most species with seven antennal flagellomeres ( Fig. 2A–C ). Gular suture incomplete. Pronotum without transverse impressed line. Elytral lateral margin with swelling at midlength associated with reception of fore leg. Males with protrochanteric setose patch ( Fig. 3A–B ). Profemora with unique setation pattern consisting of large clusters of setae arranged along the anterior and posterior margins of the ventral femoral face, becoming larger and more closely clustered apically ( Fig. 4 ).

Description. Head: Antenna of most species with 7 antennal flagellomeres; pedicel narrow, trapezoidal, mildly to noticeably narrowed apically. Labrum ventrally with 2 transverse, linear, setose rows in basal 1/2. Gular suture incomplete, lateral arms of gular suture effaced before meeting anterolateral margin of ventral epicranium, posteriad to submentum. Thorax: Pronotum without transverse impressed line. Elytral lateral mar- gin with swelling at mid-length associated with depressed cavity for reception of fore leg in meso- and metaventrites. Fore leg with protrochanter of male possessing setose patch located paramedially or apicolaterally on posterior face, absent in female; profemur ventrally with 2 linear rows of setose clusters running entire length, clusters consists of long, fine, golden setae, clusters fairly evenly spaced along most series, becoming longer, larger, more clustered in apical 1/4 of profemur, longest setose cluster ca. 1/2 width of profemur, setose clusters smaller in basal 1/4, anterior face of profemur with sinuate ventral margin, ventral margin of anterior face similar but to lesser degree, posterior face covered with short, stout setae in recessed pits, dorsal face similar but to lesser degree, absent on posterior/ventral faces; protarsomere V of female protarsus with setose furrow running near entirety of posterior face. Metaventral wing in form of nearly equilateral triangle. Metacoxal wing laterally transverse, most species with metacoxal wing ending at apex of metanepisternum. Abdomen: Abdominal sternite VIII deeply emarginate medially. Male genitalia with median lobe of aedeagus broadly articulating basomedially with parameres, lateral proximal longitudinal lists meeting median list, forming tridentshape ( Figs. 5 , 7A–C, E–G, I–K , 10 ). Female reproductive tract with medial apodeme extending anteriorly, forming continuous, strongly sclerotized bridge forming anterior to lateral boundaries of vaginal shield ( Fig. 13A–C ).

Sexual Dimorphism. Males noticeably larger in size in many populations, much more broad in body form, being laterally expanded at elytral mid-length. Protibia of very large males often with weak to very strong sinuation. Females with similar but much smaller and sparser profemoral setation. Female elytra without swelling associated with reception of fore leg.

Figures

Fig. 2. Porrorhynchus species, right antenna (anterior view above, posterior view below. A) P. landaisi, B) P. indicans, C) P. marginatus, D) P. depressus. Scale bars = 0.5 mm.

Fig. 3. Porrorhynchus marginatus, male. A) Protrochanter, marked area shows protrochanteric setose patch, scale bar = 400 μm, B) Protrochanteric setose patch, scale bar = 50 μm.

Fig. 4. Porrorhynchus marginatus, male, profemur. Scale bar = 1 mm.

Fig. 5. Porrorhynchus indicans aedeagus. A) Dorsal view, B) Lateral view, C) Ventral view. Scale bar = 1 mm.

Fig. 7. Porrorhynchus landaisi. Specimen from Hainan Island: Aedeagus in A) Dorsal view, scale bar = 1 mm, B) Ventral view, C) Lateral view, and D) Dorsal habitus, scale bar = 5 mm. Specimen from Vietnam: Aedeagus in E) Dorsal view, scale bar = 1 mm, F) Ventral view, G) Lateral view, and H) Dorsal habitus, scale bar = 5 mm. Specimen from Tibet: Aedeagus in I) Dorsal view, scale bar = 1 mm, J) Ventral view, K) Lateral view, and L) Dorsal habitus, scale bar = 5 mm.

Fig. 10. Porrorhynchus marginatus, aedeagi, lateral and dorsal views, showing populational variation. A) Mandalay District, Myanmar, B) Loei Province, Thailand, C) Khammouane Province, Laos, D) Đắk Lắk Province, Vietnam, E) Saraburi Province, Thailand, F) Chumphon Province, Thailand, G) Songkhla Province, Thailand, H) Pahang, Malaysia, I) Gunung Leuser, Sumatra, J) Siberut Island, Sumatra, K) Manna, Sumatra, L) Java, M) Kapit District, Sarawak, Malaysia, N) East Kalimantan, Indonesia. Scale bars = 1 mm.

Fig. 13. Porrorhynchus species, female reproductive tract. A) P. landaisi, B) P. indicans, C) P. marginatus, D) P. depressus, E) P. misoolensis. More heavily sclerotized areas indicated in gray. Scale bars = 1 mm.