Cygnocyphon ibex, Zwick, Peter, 2015

Zwick, Peter, 2015, Australian Marsh Beetles (Coleoptera: Scirtidae). 8. The new genera Cygnocyphon, Eximiocyphon, Paracyphon, Leptocyphon, Tectocyphon, and additions to Contacyphon de Gozis, Nanocyphon Zwick and Eurycyphon Watts, Zootaxa 3981 (4), pp. 451-490 : 453-459

Cygnocyphon ibex , n. gen. et n. sp.

( Figs. 1–8 )

Type and only species: Cygnocyphon ibex , n. sp.

Type material. Holotype ♂: Swan R. Lea [WA] ( SAMA. In poor condition, thorax and elytra on a card, head and abdomen on plastic slides in Euparal on the same pin).

Diagnosis. About 2mm long, elongate, pronotum transverse, barely narrower than the elytra, with rounded angles and slightly explanate sides. Head with buttonhole configuration ( Zwick 2013b). Mandibles with 3 teeth, maxillary palpus with very long terminal segment, labial palpus straight. Antennal base unmodified (flagellum missing). Unmodified ambulatory legs. Prosternal process very small, receiving rhomboid metaventral groove poorly developed. Penis with large bilobed pala, small cap-like trigonium and long horn-like parameroids. Tegmen and parameres flat, without major spines but with elongate invaginations armed with fine spinules. A rudimentary lateral stylus present.

Description. Habitus. BL 1.9mm, BL/BW 2.0. Head blackish, remainder brown. Head and pronotum with fine sharply defined dense punctures. Punctures on elytra much larger and deep, growing finer towards apex. Pubescence decumbent, blond. Long and slender, elytra parallel-sided, body flat ( Fig. 1 ).

Head short, a little wider than long. Eyes projecting, small, in side view almost 1/3 of their diameter above the subgenal ridge. Clypeolabrum transverse, with rounded corners. Mandibles symmetrical, strong, sharply pointed, with 3 teeth, the basal one smallest. Molar area smooth. Terminal segment of maxillary palpus long and slender, slightly concave, about twice as long as segment 3. Labial palpus straight, terminal segment long, base slightly inflated, the slender apex is blunt. Antennae missing beyond pedicel ( Figs. 2–4 ).

Pronotum strongly transverse, rather flat, the explanate sides only a little lower than the middle of the disc. Hind margin projecting towards the triangular scutellum with convex sides. Rear corners of pronotum rounded, sides converging forward, lowered towards the rounded front corners. Fore margin medially very little projecting. Legs unmodified, not saltatorial, tibiae with paired keels.

Underside. The subgenal ridge ends far from the eyes on a small raised knob and is at the level of the maxillary base separated from the raised edge of the oral cavity by a groove (sg in Fig. 2 ). In side view, the lower head contour has a small but distinct opening (buttonhole configuration, Zwick 2013b). Prosternal process very small, drop-shaped. Receiving mesosternal groove minute, indistinctly rhomboid, without delimiting ridges. There are two vertical crests on the vertical wall in front of it. The mesoventral process separates the coxae completely but is narrow and caudally truncate. It meets the metaventral process which has the form of a slender triangle. Discrimen visible over most of metaventrite. Abdominal sternites unmodified.

Male. T8 broken, a pair of straight strong apodemes and small fragments of the plate covered with microtrichia and small socketed setae remain (not shown). S8 not found. T9 with very strong straight apodemes curving caudally mediad and blending with the hind margin of the bare, short, transverse plate. S9 is a weakly sclerotized approximately rectangular caudally pilose plate ( Fig. 6 ).

Penis with very wide roundly excised pala ( Figs. 5 , 8 ). The trigonium is a short hard cupule between the very large curved horn-like parameroids. Each horn bears between base and tip a regular series of triangular incisions demarcating an appressed tooth. The tegmen ( Fig. 7 ) is a narrow rectangular sclerotized frame turning caudally into two slender lateral struts reaching back to the level of the trigonium. The struts support elongate flat blade-like parameres ending in a transverse series of fine longitudinal plicae. Each paramere possesses basally, to the inside of the struts, an elongate invagination containing delicate spinules and little toothed ribs (enlarged inset in Fig. 7 ); details not recognized. On the outside the complex of tegmen and parameres is surrounded by a tough membrane. On each side is a partly sclerotized angular basal projection which I regard as a rudimentary stylus (st in Fig. 7 ).

Female. Unknown.

Note. There is no similar Australian or Oriental species, and C. ibex fits in no known genus. In the search for relatives, negative characters like the poor development of prosternal process and mesoventral groove do not help. The buttonhole configuration occurs also in Contacyphon , Petrocyphon , and Nanocyphon whose males share a poorly developed or missing S8. Cygnocyphon may be related to this group. Nanocyphon differs in habitus, by its modified genitalia and the short conical end segment of the labial palpus. Habitus and structure are very diverse in Contacyphon but none of the few Australian species is at all similar. Even slender Contacyphon species have projecting or at least marked front angles of pronotum. Also, Contacyphon species lack a trigonium but have instead paired prosthemes. This is not the case in Cygnocyphon. The long last segment of the maxillary palpus is unique, and none of the compared genera has three mandibular teeth ( Fig. 3 ).

Etymology. It must be close to 100 years since the only specimen was taken on the Swan River. The scientific name of swans ( Cygnus ) and the historical name Cyphon are connected in allusion to the type locality. The specific name, a noun in apposition, refers to the resemblance of the parameroids with the horns of Ibex goats.

Eximiocyphon excisus , n. gen. et n. sp. ( Figs. 9–20 )

Type and only species: Eximiocyphon excisus , n. sp.

Type material. ♂ holotype: Carbine Tableland N.Qld. Upper Doolins Ck., 30 Nov 1990, 1150m, Monteith, Janetzki & Sheridan Pyrethrum Trees, logs & rocks ( QMSB).

Diagnosis. Stout, oval, moderately domed, ca 2 mm long. Slender ambulatory legs. Long antennae with unmodified scape and pedicel and minute antennomere 3. Frontoclypeus forming lateral extensions in front of antennal insertions. Mandibles without teeth. Last segment of maxillary palpus bottle-shaped, terminal segment of labial palpus inserted at an angle near middle of second segment. Pronotum at base as wide as elytra, narrowing towards straight front margin, angles blunt, not projecting. Underside: subgenal ridge ending freely in front. Prosternal process barely developed, not reaching level of coxal tips. Mesoventrite without receiving groove, mesoventral process short, triangular, not reaching the triangular metaventral process, middle coxae partly contiguous. Metacoxae transverse, their mesal portion large, square. Elytral epipleura wide in front, excavate. Male: terminal abdominal sternites with long pilosity curling around a large caudal notch on sternite 7. Genitalia long, spindle-shaped, tegmen and penis closely appressed, both with handle-like bases, penis apex asymmetrical.

Description. Habitus. BL 2.04 mm. Body stout, oval, 1.4 times longer than wide ( Fig. 9 ), moderately convex. Head large, 0.74 mm wide ( Fig. 12 ). The frontoclypeus is laterally expanded forming broad lobes in front of the antennal insertions. The labrum is small, rectangular, transverse. Mandibles slender, acutely pointed, mesal edge smooth, no teeth, undulations or setulae ( Fig. 13 ). The bottle-shaped terminal segment of the maxillary palpus is about as long as the penultimate one. Labial palpus with last segment standing at a right angle near midlength of the enlarged penultimate segment ( Fig. 15 ).

Pronotum with straight front margin, angles not projecting. Rear margin gently arched but straight in front of the scutellum which is an equilateral triangle. The irregularly punctate elytra are regularly arched, widest near midlength. There is a shallow longitudinal depression near the lateral margin in the anterior third of the elytra ( Fig. 9 ). The anterior portion of the epipleura is wide and concave ( Fig. 10 ).

Entire surface covered with simple punctures, those on the front half of body quite large, finer towards the elytral apex. The integument is shining, dark brown. The short brown setae curve forward on the head, backward elsewhere.

Antennae and legs are brown, except scape and pedicel yellowish. Antennae half as long as body. pedicel smaller than scape, antennomere 3 minute, much shorter than pedicel. Antennomeres 4 and following are cylindrical, 3–4 times as long as wide, the last with blunt tip ( Fig. 14 ). Legs slender and long (hind legs now lost), keels on the tibiae with fine spines.

Ventral face. The short gular sutures end at the tentorial invaginations from where only a faint line extends forward. Front end of the subgenal ridge unconnected, bent inward for a very short distance, parallel to the fold coming from the gular suture ( Fig. 13 ). Prosternal process minute, a low crest not reaching the level of the front coxae, no distinct groove to receive it on mesoventrite. The middle coxae are medially contiguous ( Fig. 10 ), both the mesoventral and the metaventral process are short triangles partly separating the coxae. The ventral part of the hind coxae is large, rectangular, extending outward as an almost parallel narrow strip.

Male. Sternites 3–6 unmodified, S7 with deep U-shaped notch ( Fig. 11 ). Pilosity on S6 divergent, long and curving around the notch on S7. S8 not observed. T8 ( Fig. 16 ) with long curved apodemes, the antecosta connecting them has a small forward projection in the middle. Plate long, with transparent window in middle, bare except for a fringe of fine microtrichia along the rounded caudal margin. T9 not sclerotized, transparent, free part of apodemes longer than those of T8. S9 is a small transparent anteriorly unpaired sclerite with 2 tongue-shaped caudal lobes, each with 1 or 2 small socketed setae ( Figs. 17, 18 ).

Penis and tegmen ( Figs. 19, 20 ) form a spindle-shaped complex about 1 mm long but only 0.12 mm wide. Attempts to separate parts were unsuccessful, the oblique position of the components is an artifact. The parameres are caudally narrowly divided. The long and narrow handle-like base seems to represent the tegmen, its front end is slightly widened and asymmetrical. The pale penis is a little shorter and much narrower, with long and narrow pala. The caudal third is asymmetrically divided into two long struts. The longer one has a wider base and caudolaterally a few teeth. The shorter strut has only a single minute outward tooth at the blunt tip.

Female. Not known.

Notes. The closest relative of Eximiocyphon is unknown. Each of the remarkable character expressions of this little beetle resembles some other genus. However, resemblances concern only single characters, others differ greatly. Therefore, similarities with other taxa seem to have arisen independently and provide no evidence of close relations.

• A laterally widened frontoclypeus (not to be confused with the forward projecting lobes of some Prionocyphon spp.!) occurs in some Scirtes , e.g., S. kaytae Watts. The square coxal plates also remind one of these saltatorial forms (e.g., Watts 2004: fig. 1).

• The free, slightly recurved end of the subgenal ridge resembles Scirtes spp.

• The extremely reduced prosternal process is exceptional.

• The short mesoventral process and the partly contiguous middle coxae resemble the redescription of the African-Madagascan genus Brachycyphon by Ruta (2009). However, other characters, especially the genitalia, do not fit at all.

• The spindle shape of the genitalia superficially resembles some Oriental species, e.g., the Japanese Ypsiloncyphon amami ( Yoshitomi, 2005) with a cigar-shaped penis but very different tegmen.

• The narrow handle shaped base of the penis resembles Species Group 3 of Ypsiloncyphon . Species Group 3 is endemic in Australia and New Guinea ( Zwick 2014b), the other species groups of Ypsiloncyphon are Oriental. However, there are differences in many other structures. For example, in Ypsiloncyphon the mesoventral process is well developed and often caudally widened ( Ruta 2009; Zwick 2014b).

Etymology. The genus name is an agglutination of Latin eximius, extraordinary, distinguished, with the classical name, Cyphon . It was chosen to underline that the beetle is distinguished by several unusual, presumably derived character expressions. The specific name (the Latin adjective excisus , excised) refers to the notch on S7.

Figures

FIGURES 1 – 5. Cygnocyphon ibex, n. gen., n. sp., male. 1, habitus; 2, head, combined dorsal and ventral views; 3, right mandible; 4, labial palpus; 5, terminalia. Figs. 2 – 4 to the same, 1 and 5 not to scale. gs, gular suture; sg, subgenal ridge; tt, tentorium.

FIGURES 6 – 8. Cygnocyphon ibex, n. gen., n. sp., male. 6, T 9 and S 9, superimposed; 7, tegmen, with detail of the invaginated pocket; 8, penis. Figs. 7 (excl. inset) and 8 to the same scale. st?, the presumed rudimentary stylus.

FIGURES 9 – 15. Eximiocyphon excisus, n. gen., n. sp., male. 9, body contour; 10, ventral view, after removal of head, middle and hind legs, and abdomen, diagrammatic; 11, tip of abdomen, ventral; 12, 13, head, dorsal and ventral; 14, antenna; 15, labium. Figs. 9, 10 not to scale, 12 – 14 to the same scale. c 1, c 2, c 3, pro-, meso-, and metacoxa; ms, mesoventral process; mt, metaventral process.

FIGURES 16 – 20. Eximiocyphon excisus, n. gen., n. sp., male. 16, T 8; 17, T 9; 18, S 9; 19, penis and tegmen, superimposed; 20, same, apices enlarged. 16 – 18 and 19, 20 to the same scale, respectively. pa, pala; pe, paramere; te, tegmen.