Austrocyphon Zwick, 2013, gen. n.
Creators: name: Zwick, Peter
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Scirtidae
Austrocyphon

description: Austrocyphon, gen. n.
Type species. Cyphon charon, sp. n., of which both sexes and associated larval and pupal exuviae are available.
Diagnosis. A monophylum distinguished by male genitalia: parameroids caudally fused, forming a flat structure with a transparent area (foramen) which in dorsoventral view surrounds the trigonium.
Distribution. The new genus is Australasian. Most species are endemic in Australia, one is additionally known from Papua New Guinea. Forty-one Austrocyphon species are presently recognized.
Description. Small, BL 1.8–3.1 mm, elongate-oval, widest point behind midlength, relatively flat dorsally, not highly domed. Most species uniformly brown with lighter legs, pronotal margin often diffusely lighter, some with light brown to yellow pattern on elytra. Short semi-erect hairs arise from small raised granules on head and prothorax, but arise from normal punctures on the elytra. Most often, size of punctures or granules is finest on head, increasing stepwise on pronotum, being largest on the elytra. Hairs point forward on head, about centrifugal on pronotum, medio-caudally on pronotum and on the elytra hairs point backward.
Head (Figs. 1–5) orthognathous but typically bent back and in dorsal view concealed under pronotum, retracted to the rear margin of eyes. The faint ridge delineating the neck is concealed under the pronotum, laterally it becomes stronger and continues as subgenal ridge which delimits the flat underside of head. It runs forward close to the eye in a regular curve but does not come close to it in front. Instead, the subgenal ridge eventually joins a fine line which ends at the lower mandible articulation. There is no relation with the antennal foramen. No frontoclypeal suture, frontoclypeus extending forward between antennal grooves which on the outside touch the eyes.
Antennae (e.g., Fig. 3) filiform, 11-segmented, scape wider and longer than the almost spherical pedicel, 3rd segment more slender than 2nd and 4th, relative length variable, mostly close to pedicel length. Segment 4 is usually longest. Flagellar segments are cylindrical or a little narrower at base than at tip. Last segment often a little longer, tip obtusely rounded.
Labrum a simple transverse plate with rounded corners (Figs. 1, 3). Mandibles symmetrical or almost so, both with distinct sharp apex and small to distinct tooth before apex (Figs. 2, 3). Molar area smooth, without spicules. Maxillary palpus 4-segmented, distal half of terminal segment conical, outwardly curved, bare (Fig. 4). Labium (Fig. 5) with large simple linguae and a palpiger. Labial palpus 3-segmented, penultimate segment obliquely truncate, the concave bluntly tipped terminal segment inserted terminally on preceding segment, a bit closer to inner than to outer edge so that it stands at an angle to the penultimate segment.
Pronotum a little narrower than elytra, an angle between them in dorsal view (e.g., Figs. 17, 196). Pronotum transverse, base curved forward on sides, much longer in the middle than laterally. All angles obtuse but distinct. The front angles project insignificantly to distinctly, depending on shape of front margin. This may be almost straight to slightly concave. Because the pronotum is more domed over the head and flatter near the angles, the front margin appears always sinuous, but it is not distinctly excised.
Scutellum simple, an approximately equilateral triangle.
Elytra without striae, irregularly punctate. Relatively flat, highest point of body just caudally from midlength. Humeri marked. Together, the caudal ends of the elytra form a regular parabolic curve. Total body contour in dorsal view varies with species, from oval to slender, with margins of elytra in anterior half almost parallel.
Metatergum and wings typical of the family (Lawrence 2005; Ruta & Yoshitomi 2010), no taxonomically useful traits observed. Abdominal tergites 1–7 concealed under elytra, tip of T 7 may project. T5 possesses a rudimentary, and T6 and T7 possess a regular comb of microscopic pointed cuticular processes along the very caudal edge which I call a pecten. Presence or absence of a pecten on male T8 is a useful taxonomic character (e.g., Fig. 51). The pecten of Scirtidae is similar to the multiple fringes of minute cuticular processes that winged Staphylinidae have on T7 and employ in wing folding (Székessy 1939). Hammond (1979) called the same structure a wing-toiletry device. Whether the scirtid pecten has a similar function is unknown. Scirtidae have a remarkable ability to take instantaneously to flight.
Legs short, at rest concealed under body. Femur slender, tibia with paired dorsal keels, tarsi 5-segmented with bilobed 4th segment. Claws simple.
Underside of thorax and abdomen. Prosternum with open coxal cavities separated by a keel ventrally, keel extended into a small caudally widening narrowly oval pilose plate. Receiving mesosternal groove triangular, paired tiny keels above and in front of it on the vertical anterior part of segment. Mesoventrite a narrow parallel strip between coxae, caudally narrowly excised. Metaventrite long, a short triangle projects between hind coxae, discrimen almost complete. The vertical sclerite strip bordering the metacoxae from behind includes the reduced sternites 1 and 2. Sternites 3–7 exposed, 3–6 of approximately equal length, 7th parabolic. Sternites with fine uniform pilosity. Microscopic raised hair-bearing granules may occur near middle of front margins of S4–5. Segments 7–9 modified, invaginated genital segments.
Male. Figure 6 provides an overview of the everted genitalia. Apodemes of T8 and T9 long. In T8 a transverse arched bar corresponding to the antecosta connects them at the base of the unmodified large plate. Only in a few species is T8 variously excised or notched (e.g., Figs. 167, 176, 227). The plate can be bare, or beset with socketed setae and/or microtrichia in various arrangements. Males of some groups have a pecten on T8 (e.g. Fig. 61). S8 small but distinct, represented by a V- or Y-shaped sclerite supporting minute caudolateral sclerotized patches (pteralia) with some pores and often a few small setae (e.g., Figs. 18, 28, 92).
The membranous anal cone (Fig. 6) is overlain by T9. T9 provides excellent taxonomic characters by variable degrees of reduction of the plate and transformation of its parts. In several species groups the plate is largely to completely reduced except for lateral sclerotized rods which caudally continue the anterolateral apodemes (e.g., Figs. 116, 141, 168). S9 slender, often medio-caudally notched, with some caudal pilosity, soft, barely sclerotized. The few exceptions are described under the respective species.
The tegmen basally overlying the penis has a short base (capulus) from which rise the parameres in the form of long thin lateral struts apically connected to the penis by colourless membranes. In dissected and mounted genitalia the paramere tips often appear barbed through delicate hook-like outer appendages which may be no more than bits of the torn membranes (e.g., Figs. 66, 173).
In dorsoventral view the penis is an elongate-oval structure with two membranous windows separated by a transverse sclerite bridge supporting the flat, in dorsoventral view, finger-shaped trigonium which has a more or less distinct anterior spur (Mittelblatt, lamina of Nyholm, 1972a) (e.g., Fig. 7). Shape of the basal pala variable but rarely distinctive. Trigonium with terminal claw-shaped centema often surrounded by spicules (e.g., Figs. 96, 120, 171). In some species, only a crown of spicules is present (e.g., Figs. 225, 231). The trigonium can be bent down, its tip then lies ventrally from the pala (e.g., Figs. 110, 170).
On either side of the trigonium insert the immobile parameroids which are caudally fused and together form a flat sclerite dorsally from the trigonium. This sclerite is medially membranous. In dorsoventral view, trigonium and centema stand before a membranous foramen in a surrounding sclerotized frame. Dorsolateral edges of frame in some species flanged, to different degrees (e.g., Figs. 7, 23, 174).
Female. The visible sternites 3–7 unmodified, no hair tufts, pores or other modifications. S7 caudally parabolic. T8 with separate long apodemes caudally expanding and together forming a soft truncate plate with caudal fringe of colourless microtrichia. The separate apodemes of S8 much shorter, anteriorly sinuous, the colourless plate is caudally bilobed, has some pores, a few minute sensory hairs, and marginal delicate microtrichia. Apodemes of ovipositor (segment 9) anteriorly separate, very long, with short recurrent branch shortly before the slender hairless gonocoxite. Gonostyle a short tube with about four terminal sensory pegs (e.g., Figs. 8, 144). T9 is a minute colourless plate between the gonocoxal bases.
A longitudinally folded area or a short brownish section inside the oviduct, near the apodemes of S8, is almost unsclerotized and rarely seen. It seems to be a vulvar sclerite. When distinct, the weak sclerite diverges anteriorly (Fig. 37). There is no prehensor (A. papilio has a complex sclerite in the duct to the seminal receptacle (Fig. 195) which is exceptional). The large accessory gland is bag-shaped and transparent. Its thin cuticle is covered with colourless, approximately circular depressions. From the periphery of each radiate numerous delicate folds, resembling little suns (Fig. 9).
Pupa. Known only of A. charon, sp. n. and A. spiculifer, sp. n. Habitus resembling Cyphon coarctatus Paykull, 1799, the type species of Cyphon (see figures in Zwick & Zwick 2008), with 4 long pronotal horns. Pilosity sparse. Female with two spherical caudal anchor organs on very short stalks. Male pupa not studied. In the laboratory, A. charon pupated just above the water line, on some debris or on the container wall.
Larva (Figs. 10–16). Associated specimens available only of A. charon, sp. n. and A. spiculifer, sp. n., which agree closely. Slender, light brown body with long and strong setae. A single eyespot under a weakly convex corneal area. Antennae long, tips missing, longest remaining stub of last instar larva with 57 flagellar segments. Sensillum at apex of pedicel a straight slender cone, about as long as 1.5 flagellar segments.
Clypeolabrum bilobed, ventrally deeply excised, the anteriormost spine long and slender, nearly simple, only 1 or 2 vague feathery outgrowths. About 7–8 sharply pointed spines along medial edge of each lobe, the ones basally from the big spine very thick, the inner two sickle-shaped, curved forward (Fig. 10).
Mandible of last instar with small incisivus (Fig. 12; incisivus longer in A. spiculifer). Mandibular setation continuous, not divided into two fields. Maxilla typical of the family, palpus 3-segmented, apical sensory cone indistinct (Fig, 11). Labial palpus 2-segmented (Fig. 13). General structure of hypopharynx (Fig. 13) typical of the family. The 4 setae on the keel sclerite close together, the anterior ones stouter than the others, obliquely truncate with distinct serrations. The medio-caudal setae slender, almost simple in A. charon. The 2 sensory pores longitudinally arranged on the keel sclerite. About 12 comb-teeth in a regular arch ending before the cushion, the innermost tooth sharply pointed.
Strong, long, straight setae along edges of thoracic tergites and rear margins of abdominal tergites (Fig. 15). In A. spiculifer the marginal setae are twice as long as the tergite. Abdominal tergites additionally with slightly slenderer and shorter setae near midlength, very fine and slender intercalary pilosity also present. Abdominal sternites with medially interrupted row of shorter and finer setae and only few lateral setae. S8 semicircular with numerous long setae, T8 with fewer setae, medially triangularly excised over the spiracular openings which touch medially. S9 semicircular, margin with minute brush-like setae. T9 also semicircular, with short nipple-like process bearing 2 setae (Fig. 16).
Legs short, with strong spines (Fig. 14). Tarsal claw about half as long as tibiotarsus, with two setae near midlength. Tibiotarsal organ on front leg (Zwick 2008) inconspicuous and simple, composed of only few small stout setae in A. charon, about 8 slender straight setae in a row in A. spiculifer.
description: Published as part of Zwick, Peter, 2013, Australian Marsh Beetles (Coleoptera: Scirtidae) 4. Two new genera, Austrocyphon and Tasmanocyphon, pp. 1-74 in Zootaxa 3706 (1) on pages 7-11, DOI: 10.11646/zootaxa.3706.1.1, http://zenodo.org/record/284605