Porrorhynchus depressus, Regimbart 1892 b: 996

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

Porrhorrhynchus depressus Régimbart 1892b: 996 [original description], 1902: 5 [distribution].

Dineutus (Rhomborhynchus) depressus: Ochs 1929c: 200 [holdings], 1955: 133 [redescription].

Dineutus (Rhomborhynchus) depressus jamurensis Ochs 1955: 133 [original description]. New synonymy.

Dineutus (Rhomborhynchus) depressus versteegi Ochs 1955: 134 [original description]. New synonymy.

Dineutus (Rhomborhynchus) depressus moszkowskii Ochs 1955: 134 [original description]. New synonymy.

Porrorhynchus (Rhomborhynchus) depressus: Brinck 1955: 103 [new status].

Porrorhynchus (Rhomborhynchus) depressus depressus: Polhemus 2011: 52 [locality and habitat].

Type Material Examined. Porrorhynchus depressus Régimbart, 1892 : Holotype (♂ card mounted, with aedeagus glued to card, missing labrum, Fig. 17B ): “N. Guinea / Dilo/ Loria Vi.VII.90 [beige label, typed black ink with black border]// Typus [beige label, typed red ink with red border]// “Porrhorrhynch./ depressus/ Reg. n.sp. [beige label, handwritten in black ink, handwriting appears to be Régimbart’ s]// depressus / Rég. [beige card label, handwritten in black ink, unknown handwriting, black border]// Porrhorhynch./ depressus/ typus! Rég. [yellow label, handwritten in black ink, unknown handwriting]// Museo Civico/ di Genova [beige label, typed black ink]// Dineutus / ( Rhomborhynchus )/ depressus Rég. / vid. Ochs 1954 [beige label, typed black ink]// Vidit P. Brinck,/ 1982-2006 [white label, typed black ink]// HOLOTYPUS / Porrorhynchus / depressus/ Regimbart, 1832 [red label, HOLOTYPUS typed in black ink, rest handwritten in black ink, handwriting unknown]//” ( MSNG).

Dineutus (Rhomborhynchus) depressus jamurensis Ochs, 1955 : Paratypes (♂ pinned, with aedeagus on point, Fig. 17C ): “ ♂ [white label, black typed ink]// B Jamoer/ 4 VIII 1903 [white label, handwritten in ink, handwriting unkown]// Coll./ G.Ochs [white label, typed black ink]// Para-/ typoid [red label with black border, typed black ink; underneath handwritten in black ink SMF C 9535 ]// jamurensis/ Ochs [beige label with black border, handwritten in blue ink, handwriting appears to be Ochs’]//” ( SMF); (♀ pinned): Same as previous except with ♀ label and underneath Para-typoid label handwritten in black ink SMF C 9536, without jamurensis Ochs label ( SMF) .

Dineutus (Rhomborhynchus) depressus moszkowskii Ochs, 1955 : Holotype (♂ pinned, with aedeagus on point, Fig. 17E ): “ ♂ [white label, typed black ink]// Holl. N.- Guinea / Zentralgeb. Ende XII.10/ Moszkowski S.G. [gray label, typed in black ink, except Zentralgeb. Ende XII.10 handwritten, handwriting uknown]// 94915 [beige label, handwritten in black ink, handwriting unknown]// Coll./ G.Ochs [white label, typed black ink]// Typus [red label with black border, typed black ink; underneath handwritten in black ink SMF C 9538 ]// moszkowskii/ Ochs [beige label with black border, handwritten in blue ink, handwriting appears to be Ochs’]// ” ( SMF). P aratype (allotype) (♀ pinned): Same label data as holotype except with ♀ label and “Allo-/typus [red label with black border, Allo- hand written in black ink, rest typed black ink; underneath handwritten in black in SMF C 9539 ]//” ( SMF).

Dineutus (Rhomborhynchus) depressus versteegi Ochs, 1955 : Holotype (♂ pinned, with aedeagus on point, Fig. 17F ): “ ♂ [white label, type black ink]// Z. NieuwGuinea / Versteeg 1912.13/ Beaufort. II [white label, typed black ink, except Beaufort. II handwritten in black ink]// [blue label, underneath typed in black ink 1919, plus some illegible scribble in pencil]// Museum/ Dresden/ leg. 1928. [white label with thin black border, typed black ink]// Coll./ G.Ochs [white black, typed black ink]// Typus [red label with thick black border, typed black ink; underneath handwritten in black ink SMF C 9537 ]// versteegi Ochs [beig label with black border, handwritten in blue ink, handwriting appears to be Ochs’]//” ( SMF) . Paratype (♀ pinned): Same locality label as holotype except with ♀ label, as well as “Para-/ typoid [red label with black border, typed black ink; underneath handwritten in black ink SMF C 11258]// det. K.M.HELLER 1915/ Porrorhynchus / depressus Rég. [beige label, typed black ink, except 15 handwritten in black ink]//” and without blue label and versteegi Ochs label ( SMF) .

Type Material Notes. Upon initial receipt of the type specimens of P. depressus moszkowskii from SMF, close examination revealed that what had been indicated as the male holotype based on the type labels ( SMF C 9538 ), as well as a male symbol label and pointed aedeagus, was in fact a female specimen. The specimen with the allotype label ( SMF C 9539 ) and female symbol label was a male specimen whose abdomen was propped open, indicative of dissection. It appears that at some point during a past examination all the male holotype labels, including the dissected genitalia, were removed, as were those of the female allotype, at which point they were subsequently switched upon being returned to the specimens. Ochs (1955) was explicit when he designated a male as the holotype and a female allotype. Therefore, since it is clear that the male specimen received from SMF was previously dissected and carrying allotype labels, and was likely switched with the female holding the holotype labels, the holotype labels were returned to the dissected male specimen and the allotype labels were placed back on the female specimen received .

Additional Material Examined. INDONESIA: West Papua (" Irian Jaya "): Nabire, 30km S. Nabire, Kali Cemara , 150m, 15.viii.1998, leg. M. Balke, CE 1 (29 ex. NHMW) ; Nabire, rd. Nabire-Ilaga, Km 35 Kali Cemara , 100m, 27.ix.1997, leg. M. Balke, IRS97#6 (41 ex. NHMW) ; Nabire, rd. Nabire-Ilaga, Km 63, 8.x.1997, leg. M. Balke, IRS97#9 (62 ex. NHMW) ; Danau Yamur (" B Jamer ”), 4.viii.1905 ,

Coll. MAURICE REGIMBART 1908 (1 ex. MNHN) ; same as previous except: coll. C.L. Legros (1 ex. MNHN) ; "Nelle Guinea Limmena", Danau Yamur (" B Jamer ”), 4.viii.1905, Coll. MAURICE REGIMBART 1908 (2 ex. MNHN) . PAPUA NEW GUINEA: 1912-1913, leg. Versteeg, ZML.2010/ 334,335 (2 ex. MZLU) . Central

Province: " Astrolabe Geb.", leg. E. Weiske, ZML.2010/ 333 (1 ex. MZLU). Gulf Province: Omo River, at Omo , 6°58'41"S 144°18'15"E, 40m, 28.ii.1995, leg. D.A. Polhemus, CL 7001 (6 ex. DAPC) .

Type Locality. Dilo village , Central Province, Papua New Guinea .

Diagnosis. Labrum elongate and in the form of a near equilateral triangle. Antenna with six flagellomeres ( Fig. 2D ). Dorsally bronzy brown, with pronotal yellow lateral margins broad, completely reaching lateral boundary of pronotum ( Fig. 1D ). Yellow lateral margins complete on elytra, extending to elytral apices, never interrupted in basal third by a dark spot, elytra without swelling associated with reception of fore leg in males ( Fig. 1D ). Elytra broadest at mid-length, apices spinose, apicolaterally without sawtoothlike spines, sutural angle produced to a short point, one large parasutural spine, epipleural angle with a large spine ( Fig. 1D ).

Porrorhynchus depressus can be distinguished from most other species of the genus in having spinose elytral apices without apicolateral triangular sawtooth-like spines and from P. misoolensis by the form of the aedeagus and gonocoxae of the female RT. The aedeagus of P. depressus is parallel-sided for four-fifths its length, straightly narrowed towards apex in apical fifth, and nearly as long as the narrow parameres, whereas that of P. misoolensis is abruptly expanded laterally in its apical three-fourths, then roundly narrowed towards its apex in the apical fourth, and distinctly shorter than the broader parameres. The gonocoxae of P. depressus are narrower and more elongate in appearance, with their apices narrowly rounded, compared to those of P. misoolensis which has broader, less elongate gonocoxae. In general, P. depressus is larger in body size and has a broader dorsal habitus, with elytra that are typically much more laterally expanded. The lateral expansion of the elytra occurs near midlength, as opposed to just anteriad mid-length, as in P. misoolensis .

Description. Size: ♂ L: 9.5 – 11.5 mm, W: 5.5–7.0 mm; ♀ L: 9.6–11.6 mm, W 5.2–7.1 mm. Habitus: Small member of genus; body form often tear-drop-shaped, broadest posteriad middle, attenuated anteriorly and posteriorly, other populations elongate oval, evenly attenuated anteriorly to posteriorly; in lateral view, fairly depressed, weakly humped in scutellar region, depressed posteriorly and anteriorly; in anterior and posterior views, weakly sloped towards lateral margins, lateral margins explanate. Coloration: Dorsally head, pronotum, and elytra bronzy brown; labrum of uniform color, similar to head; pronotum/ elytra with yellow lateral margins; elytral margin uniformly yellow, only darkened at epipleural spine; venter yellow; ultimate maxillary palpomere not darkened; fore legs with tibia somewhat darker in proximal 1/2, profemora shortly darker apically. Head: Vertex with fairly even covering of lightly impressed, fine punctures, often obscured by strongly reticulation, most readily visible in lateral view, separated from nearest puncture by ca. 2–3X diameter of a puncture; orbital ridge without yellow margin; punctation on frons similar to vertex, sparser, punctures sparsest apicomedially, fronto-lateral margins lightly wrinkled, frontoclypeal suture with posterior margin nearly straight, lateral margins shallowly arched, meeting posterior margin at ca. 130° angle; clypeus with punctation most evident at anterior margin, sparsest medially, punctures separated from nearest puncture by ca. 3–4X diameter of a puncture, becoming more densely spaced anteriorly and laterally; antennal flagellum with 6 complete flagellomeres, ultimate flagellomere ca. 3X longer than penultimate, trapezoidal; labrum in form of equilateral triangle, punctation absent basomedially, in association with strong reticulation, strongly present apically, punctation more strongly impressed, separated from nearest puncture by 1–2X diameter of a puncture; maxillary and labial palpi similar in shape ( Fig. 11C ), strongly hatchet-form; anterior margin of maxillary palp and ventral margin of labial palp evenly curved, posterior margin of maxillary palp and dorsal margin of labial palp more strongly curved proximally, nearly straight apically, apex of both truncate. Thorax: Pronotum with even covering of fine, weakly impressed punctures, most evident medially, nearly imperceptible laterally, punctures separated from nearest puncture by 1–2X diameter of a puncture, reticulation less impressed medially, becoming very well-impressed laterally, shallow transverse depression often present medially, lateral marginal depression absent; protibial spine projecting anterolaterally; male protarsi narrow, somewhat dorsally convex, shape as in Fig. 11A , ultimate protarsomere of male ca. 2X as long as wide, penultimate protarsomere slightly larger than previous 3; ultimate protarsomere of female ca. 0.5X longer than penultimate; elytra with uniform reticulation, elytral discs with even covering of very weakly impressed, fine punctation, nearly imperceptible, distance between nearest punctures ca. 4–5X diameter of a puncture, punctures more closely spaced at suture; lateral marginal depression absent, elytral margins evenly sloped, weakly explanate; yellow lateral margin complete, ending apicolaterally at epipleural spine, never interrupted in basal 1/3 by darkly colored spot, males without swelling associated with cavity for reception of foreleg; apicolateral margins of elytra without triangular sawtooth-like spines, epipleural angle produced as spine, elytral apices spinose ( Fig. 1D ), with 1 parasutural spine, sutural angle produced; mesoventral apex shortly acuminate with broad apex; meso- and metacoxae dissimilar, mesocoxae without posteriorly projecting process; metacoxal process with distinct lobes ( Fig. 11B ); male mesotarsal claws as in Fig. 11L , with ventral margin strongly arched, anterior claw not significantly narrowed apically. Genitalia: Aedeagus ( Fig. 12A–C, E–G, I–K ) with median lobe nearly as long as parameres, just shorter in some populations, parallelsided for 4/5 length, narrowed towards apex in apical 1/5 with straight apicolateral margins, carinate in apical 1/6, apex in lateral view subtruncate, median lobe evenly arched dorsally; parameres in dorsal view narrow, setose in apical 1/2, weakly laterally expanded in apical 1/2, shallowly arched towards apex, apex flatly rounded, basally with narrow basal bridge; in lateral view, ventral margin of parameres very weakly curved anteriorly to posteriorly. Female reproductive tract ( Fig. 13D ) with narrow, elongate, tubiform spermatheca; gonocoxae elongate and narrow, apically narrowly rounded.

Sexual Dimorphism. No sexual dimorphism appears evident. The only differences are those mentioned in the description of the subgenus.

Variation. Porrhorrhynchus depressus is variable in the extent of the lateral expansion of the elytra. Specimens from more eastern regions exhibit a broader dorsal habitus ( Fig. 12D, H ) from the greater lateral expansion of the elytra, while those from the western part of the range are narrower, with the elytra only slightly expanded laterally ( Fig. 12L ).

Distribution. This species can be found across New Guinea ( Fig. 15 ).

Biology. This species is known primarily from rivers, and one locality is described in detail by Polhemus (2011). Older records also include the lake Danau Yamur, but it is unclear if P. depressus was collected on the lake or from streams near or feeding the lake, the latter being more likely.

Discussion. Four subspecies of P. depressus were described by Ochs (1955), all from very few specimens from disparate localities across New Guinea. The subspecies P. depressus jamurensis was described from Danau Yamur in northwestern New Guinea based upon minor variation in the yellow lateral margins of the elytra and parameres of the aedeagus. The subspecies P. depressus versteegi was described from the “Beaufort River”, described by Ochs (1955) as a tributary of the Lorentz River, distinguished as being slightly larger and broader than the nominal species, and associated with minor aedeagal variation. Finally, P. depressus moszkowskii , described from the Van Daalen River, was separated by Ochs (1955) due to its smaller size and narrower body form. These minor variations in body size, outline, and parameres served as the basis for separating these subspecies from the typical form from southeastern New Guinea.

As can be seen in Fig. 12D, H, L , there is considerable variation in degree of lateral expansion of the elytra, creating a relatively broader or narrower dorsal habitus among populations. Newly examined specimens from Nabire are considerably narrower than the southeastern populations, more so than any other previously described subspecies, but similar significant variation is not exhibited in other morphological features ( Fig. 11A–L ). As seen with other Porrorhynchus species , the parameres tend to vary considerably among populations (i.e., P. marginatus ), but the median lobes tend to be fairly conserved. The most noticeable variation among the median lobes is exhibited in the degree of acumination in the apex. Specimens from Nabire ( Fig. 12I ) are more weakly constricted relative to typical specimens ( Fig. 12A ), while those from the Lorentz River (corresponding to P. depressus versteegi , Fig. 12E ) are more strongly acuminate. However, all median lobes of all populations are similarly proportioned, being nearly as long as the parameres, with the following similar features: mostly parallel-sided for nearly entire length; acuminate in the apical fifth; and with a carinate apex. For this reason, all of the former subspecies are here synonymized based on simple populational variation.

This species has not yet been implicated as being sensitive to water quality. Polhemus (2011) very infrequently encountered this species compared to other New Guinean gyrinids ( Polhemus 2011), and its scarcity in museum collections suggests it may be rare. We here propose the common name of flat snouted whirligig for P. depressus .

Figures

Fig. 17. Type specimens. A) Porrorhynchus marginatus, holotype and label, B) Porrorhynchus depressus, holotype, C) Dineutus depressus jamurensis, paratype, D) Porrorhynchus tenuirostris, lectotype and labels, E) Dineutus depressus moszkowskii, holotype, F) Dineutus depressus versteegi, holotype, G) Dineutus marginatus mjobergi, lectotype and labels, H) Dineutus depressus misoolensis, paratype.

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. 1. Porrorhynchus species, dorsal habitus. A) P. marginatus, B) P. landaisi, C) P. indicans, D) P. depressus, E) P. misoolensis. Scale bar = 5 mm.

Fig. 11. Porrorhynchus species. P. depressus from Gulf Province, Papua New Guinea: A) Protarsus, B) Metacoxal apex, C) Maxillary (above) and labial (below) palpi, D) Mesotarsal claw. P. depressus from the Lorentz River, southwestern Irian Jaya: E) Protarsus, F) Metacoxal apex, G) Maxillary (above) and labial (below) palpi, H) Mesotarsal claw. P. depressus from Nabire, western Irian Jaya: I) Protarsus, J) Metacoxal apex, K) Maxillary (above) and labial (below) palpi, L) Mesotarsal claws. P. misoolensis: M) Protarsus, N) Metacoxal apex, O) Maxillary (above) and labial (below) palpi, P) Mesotarsal claws. Scale bars = 0.5 mm.

Fig. 12. Porrorhynchus species. P. depressus from Omo River, Gulf Province, Papua New Guinea: Aedeagus in A) Dorsal view, scale bar = 1 mm, B) Ventral view, C) Lateral view, and D) Dorsal habitus, scale bar = 5 mm. P. depressus from Lorentz River, southwestern Irian Jaya: Aedeagus in E) Dorsal view, scale bar = 1 mm, F) Ventral view, G) Lateral view, and H) Dorsal habitus, scale bar = 5 mm. P. depressus from Nabire, western Irian Jaya: Aedeagus in I) Dorsal view, scale bar = 1 mm, J) Ventral view, K) Lateral view, and L) Dorsal habitus, scale bar = 5 mm. P. misoolensis: Aedeagus in M) Dorsal view, scale bar = 1 mm, N) Ventral view, O) Lateral view, and P) Dorsal habitus, scale bar = 5 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.

Fig. 15. Map showing distribution of species in the subgenus Rhomborhynchus. Triangles = P. depressus; circle = P. misoolensis.