Bioacoustics of Pterinoxylus

Description: ♀♀ / ♂♂ . Medium sized to large (body lengths: ♀♀ incl. subgenital plate 116.0–196.0 mm, ♂♂ 82.0– 118.0 mm), elongate and moderately slender, stick-like Cladomorphinae with very prominent sexual dimorphism. ♂♂ with scale-like tegmina and alae exceeding abdominal tergum IV. ♀♀ much larger and much stockier, brachypterous but alae projecting over posterior margin of median segment. Alae with a tympanal area (= stridulatory organ) in the basal portion of the costal region, that is positioned between the radial and medial veins ( Figs. 20A–B ); radial vein notably thickened, domed and with rough dorsal texture. Body of ♂♂ cylindrical, of ♀♀ subcylindrical. Entire body surface ± prominently rugulose and wrinkled, thorax partly granulose, tuberculose or spinose. Head longer than wide, dorsoventrally flattened and ± parallel-sided. Vertex with ± prominent tubercles or spines and occasionally convex. No ocelli. A slender and transverse gula present. Antennae moderately robust and not reaching ( ♀♀ ) or slightly projecting over posterior margin of mesothorax; consisting of 27–33 segments. Scapus dorsoventrally flattened and ± roundly deflexed laterally, pedicellus subcylindrical. Following antennomeres with a longitudinal median keel or bulge ventrally. Pronotum rectangular and distinctly longer than wide. Probasisternum with two rough sensory areas near lateral excavations of procoxae ( Figs. 1B–C ); profurcasternum with a raised, oval central sensory area ( Figs. 1B, 1D ). Mesothorax elongate, at least 3x longer than pronotum (comparatively longer in relation in ♂♂ ), parallelsided. Metanotum quadrate to slightly transverse. Meso- and metasternum as well as pleurae simple; granulose, rugulose and/or tuberculose. Tegmina ovate and scale-like with a rounded central hump; slightly projecting over posterior margin of metanotum. Anal region of alae dark grey to black with ± distinct transparent spots, markings or radially arranged stripes; in ♀♀ of a conspicuous convex contour when opened. Abdomen longer than head and thorax combined. Median segment about 2x longer than metanotum. Segments II–VI parallel-sided and either more than 2x longer than wide ( ♂♂ ) or just indistinctly longer than wide ( ♀♀ ). Tergum VII parallel-sided to ± laterally deflexed and sometimes with a lateral lobe ( ♀♀ in particular). VIII–X slightly narrower ( ♀♀ ) or a little broader than previous segments ( ♂♂ ). Praeopercular organ of ♀♀ indistinct and usually formed by a median tubercle close to posterior margin of sternum VII. Anal segment quadrate to slightly transverse, the posterior margin rounded with a small median indentation ( ♂♂ ) or broadly emarginated ( ♀♀ ). Epiproct small and with a longitudinal median carina, mostly concealed by anal segment in ♂♂ . Vomer of ♂♂ well developed, sclerotized and broadly triangular with a single, fairly short, upcurved terminal hook ( Figs. 21A–F ). Cerci very small, compressed laterally, ± carinate dorsally and ventrally and slightly incurved. Gonapophyses VIII of ♀♀ not considerably elongated or extending beyond anal segment but notably longer than gonaphophyses IX ( Fig. 1A ). No gonoplacs. Gonangulum present. Subgenital plate of ♀♀ elongate, irregularly naviculate or spatulate and distinctly projecting over apex of anal segment; longitudinally keeled basally but broadened and flattened towards a rounded to angular apex. Poculum (= subgenital plate) of ♂♂ gently convex, cup-like and with a median carina; posterior margin notched medially. Legs short and robust ( ♀♀ in particular) with more or less prominently expanded or lobed carinae. Tibiae notably shorter than corresponding femora. Protibiae with broad foliaceous lobes and lamellate expansions ( ♀♀ in particular). Meso- and metafemora and corresponding tibiae with a ± distinct sub-apical dorsal lobe or tooth. Profemora shorter than mesothorax, metafemora at best reaching half way along abdominal tergum IV. Profemora compressed and curved basally and distinctly triangular in cross-section with the anterodorsal carina conspicuously raised and ± lamellate; medioventral carina indistinct and slightly displaced towards anteroventral carina. Meso- and metafemora and all tibiae trapezoidal in cross-section, the two anterior carinae strongly approaching each other. Medioventral carina of meso- and metafemora indistinct and unarmed or at best with a few minute spinules. Meso- and metatibiae shorter than corresponding femora. Tibiae without an area apicalis. Medioventral carina of meso- and metatibiae conspicuously displaced towards the anteroventral carina in the median portion. Tarsi short and stout, probasitarsus with a distinct rounded dorsal lobe, that is formed by the melted dorsal carinae. Meso- and metabasitarsi simple, furcate dorsally with the two dorsal carinae strongly approaching each other but well separated, and no longer than following two tarsomeres combined. Eggs ( Figs. 22A–H ): Large to very large (overall length> 6.0 mm), alveolar, at least 3x longer than wide and cylindrical to oval in cross-section. Entire capsule surface minutely punctured and strongly sculptured, with prominent raised ridges and wrinkles. Polar-area with a more or less prominent, hollow peripheral extension. Operculum circular and with a peripheral extension on outer margin similar to that of the polar-area. Micropylar plate elongate, oval and pointed anteriorly; covering about one-quarter of capsule length. Micropylar cup distinct. Internal micropylar plate open with a wide, triangular posteromedian gap. No median line.

Description: ♀♀/♂♂ ( Figs. 37–38 ). Medium sized to large (body lengths: ♀♀ incl. subgenital plate 135.0–189.0 mm, ♂♂ 94.0–118.0 mm), elongate and moderately slender, stick-like, brown Cladomorphinae with distinct sexual dimorphism. ♂♂ with scale-like tegmina and alae exceeding abdominal tergum IV. ♀♀ brachypterous and alae with a tympanal area (= stridulatory organ) in the basal portion of the costal region; alae projecting over posterior margin of median segment. Body of ♂♂ cylindrical, of ♀♀ subcylindrical. Entire body surface ± prominently rugulose and wrinkled, thorax partly granulose or tuberculose. Mesothorax of ♂♂ occasionally spinulose. Head longer than wide, dorsoventrally flattened and ± parallel-sided. Vertex with ± prominent tubercles or spines and occasionally slightly convex ( Figs. 39–40 ). No ocelli. A slender and transverse gula is present. Antennae moderately robust and not reaching (♀♀) or slightly projecting over posterior margin of mesothorax; consisting of 30–40 segments. Scapus dorsoventrally flattened and roundly deflexed laterally, pedicellus subcylindrical. Following antennomeres with a longitudinal median keel or bulge ventrally ( Figs. 39–40 ). Pronotum rectangular, distinctly longer than wide and longer than head. Probasisternum with two rough sensory areas near lateral excavations of procoxae ( Figs. 41, 43 ); profurcasternum with a raised, oval central sensory area ( Fig. 42 ). Mesothorax elongate, at least 2x longer than head and pronotum combined (longer in ♂♂), parallel-sided. Metanotum quadrate to slightly transverse. Meso- and metasternum as well as pleurae simple. Tegmina ovate and scale-like with a rounded central hump; slightly projecting over posterior margin of metanotum. Anal region of alae dark grey to black with ± distinct transparent spots, markings or radially arranged stripes; in ♀♀ of a conspicuous convex contour when opened. Abdomen longer than head and thorax combined. Median segment about 2x longer than metanotum. Segments II–VI parallel-sided and either more than 2x longer than wide (♂♂) or just indistinctly longer than wide (♀♀). Tergum VII ± laterally expanded or with a lateral lobe (♀♀ in particular). VIII–X slightly narrower (♀♀) or a little broader than previous segments (♂♂). In ♀♀ tergites III–IX often with a posteromedian tubercle. Praeopercular organ of ♀♀ indistinct and usually formed by a median tubercle close to posterior margin of sternum VII. Anal segment quadrate to slightly transverse, the posterior margin rounded with a small median indentation (♂♂) or broadly emarginated (♀♀). Epiproct small and with a longitudinal median carina; posterior margin truncate. Vomer of ♂♂ well developed, sclerotized and broadly triangular with a single short terminal hook ( Fig. 36 ). Cerci very small, subcylindrical and slightly in-curving. Gonapophyses VIII of ♀♀ short, not extending beyond anal segment. No gonoplacs. Subgenital plate of ♀♀ elongate, irregularly naviculate or spatulate and distinctly projecting over apex of anal segment; longitudinally keeled basally but broadened and flattened towards a rounded to angular apex. Poculum of ♂♂ gently convex, cup-like and with a median carina; posterior margin notched medially. Legs short and robust (♀♀ in particular) with more or less prominently expanded or lobed carinae. Protibiae with broad foliaceous lobes and expansions (♀♀ in particular). Meso- and metafemora and corresponding tibiae with a ± distinct sub-apical dorsal lobe or tooth. Profemora shorter than mesothorax, metafemora at best reaching half way along abdominal tergum IV. Profemora compressed and curved basally and distinctly triangular in cross-section with the anterodorsal carina conspicuously raised and ± lamellate; medioventral carina indistinct and slightly displaced towards anteroventral carina. Meso- and metafemora and all tibiae trapezoidal in cross-section, the two anterior carinae strongly approaching each other. Medioventral carina of meso- and metafemora indistinct, and unarmed or at best with a few minute spinules. Tibiae without an area apicalis. Medioventral carina of meso- and metatibiae conspicuously displaced towards the anteroventral carina in the median portion. Tarsi short and stout, probasitarsus with a distinct rounded dorsal lobe, that is formed by the melted dorsal carinae. Meso- and metabasitarsi simple, furcate dorsally with the two dorsal carinae strongly approaching each other but well separated, and no longer than following two tarsomeres combined. Eggs ( Figs. 44 & 46 ): Very large (overall length> 8.0 mm), alveolar, at least 3x longer than wide and cylindrical to oval in cross-section. Entire capsule surface minutely punctured and strongly sculptured, with prominent raised ridges and wrinkles. Polar-area with a more or less prominent, hollow peripheral extension. Operculum circular and with a peripheral extension on outer margin similar to that of the polar-area. Micropylar plate elongate, oval and pointed anteriorly; covering about ¼ of capsule length. Micropylar cup distinct. Internal micropylar plate open with a wide, triangular posteromedian gap. No median line ( Fig. 46 ).

Differentiation ( Table 2 ): Pterinoxylini n. trib. is closely related to Hesperophasmatini and Haplopodini, with which the increasingly shortened gonapophyses VIII and lack of gonoplacs of ♀♀ and lack of a median line in the eggs are shared. The presence of sensory areas on the probasisternum and profurcasternum are shared with Hesperophasmatini and support a sister-group relationship with this tribe. The new tribe is characterised by: the distinctly triangular cross-section of the profemora; broadly expanded and lamellate carinae of the protibiae; dorsally lobed probasitarsus; longitudinal carina along the ventral surface of the basal antennomeres; distinctly displaced medioventral carina of the meso- and metatibiae (towards anteroventral carina); strongly laterally deflexed scapus; presence of a gula and possessing rough, oval sensory areas on both the probasisternum and profurcasternum of both sexes ( Figs. 41–43 ). The presence of a gula is most certainly a plesiomorphic character state, because it is present in all three tribes of Cladomorphinae sensu stricto , and readily distinguishes Pterinoxylini n. trib. from Hesperophasmatini and Haplopodini. Females are furthermore characterised by the conspicuous tympanal area (= stridulatory organ) in the basal portion of the alae (see discussion below), which seems to be an autapomorphy of the tribe because it is unique within the entire Cladomorphinae . Males are well recognized by the colouration of the anal region of the alae, which is grey to black and furnished with a variable number of transparent oval spots ( Fig. 38 ). The eggs readily differ from those of Hesperophasmatini and Haplopodini by their remarkable size, very elongate and alveolar capsule which is at least 3x longer than wide, as well as the hollow, peripheral or crest-like extensions of the polar-area and operculum ( Fig. 44 ). In addition to characters mentioned above the new tribe also differs from Hesperophasmatini by the much larger size as well as the considerably more elongate and slender body (♀♀ in particular). Sensory areas on the probasisternum and profurcasternum are also present in most Hesperophasmatini (→ 4.2.4), but the evaginations are much shorter, rather cone-shaped and have a deep central pit.

The following three interesting and taxonomically important key features warrant a more detailed recognition: 1. Stridulatory organ. If disturbed, live ♀♀ produce a stridulating sound, which is produced by scraping the rough basal portion of the alae by the down-curving posterior margin of the tegmina. The basal half of the prominent radial vein of the alae is dorsally covered with numerous very minute rasp-like tubercles, and together with the median and cubital vein forms a conspicuous more or less oval, sub-basal membrane or typhanal area, which is of a considerably thinner diameter than the rest of the costal region. In scraping these rasps by the sharp and hard posterior edge of the tegmina, a rustling sound is produced that is presumably increased by vibration of the tympanal area of the alae. In addition, the convex and dome-like shape of the tegmina may serve to increase the sound by resonance. This stridulating sound has so far only been reported to be produced by ♀♀, but if the alae of ♂♂ are spread a similar but much more slight sound can be observed. As in ♀♀ the radial vein of the alae is very prominent in its basal portion and covered with the same rasp-like tubercles, but interestingly no tympanal area is developed, perhaps the reason why the sound is by far not as loud as in ♀♀. 2. Alae of ♀♀: In addition to exhibiting a stridulatory organ in the costal region of the alae, ♀♀ of Pterinoxylus are typical for having the anal region of a conspicuously convex contour. This makes the conventional spreading of the wings in preserved specimens almost impossible, due to the outer margin curves increasingly downward as the wing is opened. This has already been pointed out by Rehn (1957: 188, footnote 9). 3. Sensory areas. The probasisternum and profurcasternum of both sexes show rough sensory areas very similar in structure to those seen in the closely related Hesperophasmatini , and a priori are homologous to the Oriental Heteropterygidae and certain Neotropical Pseudophasmatidae : Xerosomatinae : Xerosomatini . The probasisternum bears two sensory areas, one each at the excavation of the procoxae ( Figs. 41, 43 ), and the profurcasternum has one central sensory area, which is much larger than those of the probasisternum and easily seen without magnification ( Fig. 42 ). On the probasisternum they are formed by a conspicuous, convex and slightly transverse, white hump which dorsally bears numerous minute, cone-like evaginations each of which has a central pit or hollow. These evaginations are circular in cross-section, pale to mid brown basally and dark brown at the apex. Occasionally, there are two further, much smaller sensory areas interior of the two large outer ones. The prominent sensory area of the profurcasternum is of a slightly different structure, being formed by an oval, central cluster of rounded, whitish granules each of which bear a cluster of 2–6 of the same cone-like evaginations seen on the sensory areas of the probasisternum ( Fig. 42 ). The function of these sensory areas is still unknown, but due to the central hollow seen in each of the numerous small evaginations, they appear to serve as tactile or olfactory organs. An ultrastructural study of these organs appears necessary for any broader discussion (Bradler, 2009: 32).