Debrona cervina Walker, 1870

Naskrecki, Piotr & Guta, Ricardo, 2019, Katydids (Orthoptera: Tettigoniidae) of Gorongosa National Park and Central Mozambique, Zootaxa 4682 (1), pp. 1-119 : 88-90

Debrona cervina Walker, 1870

http://lsid.speciesfile.org/urn:lsid: Orthoptera .speciesfile.org:TaxonName:12552

( Figs. 38 A–H, 54D–F)

Diagnostic remarks. A striking, large katydid, easily identifiable by the combination of broad, opaque tegmina and bright orange hind wings (the color sometimes fades in preserved specimens) ( Fig. 38D ), brown spots around the male stridulatory area ( Fig. 38H ), and a very short, pointed ovipositor ( Fig. 38F ). Males of D. cervina can be confused with those of Horatosphaga serrifera , especially since both species have bilaterally closed tympana on the front tibia. They can be distinguished by the orange coloration of the hind wings, an elongate subgenital plate and evenly curved cerci ( Fig. 38B ), and the absence of dense spines on the ventral edges of the hind femur in D. cervina . In H. serrifera the hind wings are clear, the male subgenital plate is trapezoidal, the cerci are straight with only the apical part incurved, and the ventral edges of the hind femur carry distinct dark spines along their entire length.

Bioacoustics. D. cervina , along with Oxyecous lesnei , are unique among known katydids in being able to stridulate while flying. This interesting behavior, its mechanism, and potential adaptive advantage will be discussed in an upcoming publication (Naskrecki, in prep.) In addition to in-flight stridulation both species also stridulate while in a stationary position in the forest canopy. The stationary call of D. cervina is acoustically identical to the one produced while flying and consists of a long, uninterrupted series of syllables produced every 0.9– 2.0 s; mean syllable duration is 0.26 s (SD=0.0342, n=25); the peak frequency of the call is 5.9–6.4 kHz, with a strong harmonic at 11.7–12.3 kHz ( Figs. 54 D–F). The call is very loud and audible from a distance of at least 100 m.

Distribution and natural history. D. cervina , originally described from South Africa and Tanzania (as Otiaphysa hebetata Karsch, 1889 , subsequently synonymized by Kirby [1906]), has since been found also in Zimbabwe and Mozambique (see material examined), indicating that this species is widely distributed across southern and East Africa. These insects are strong fliers, found in a variety of woodland and open habitats, making its wide dispersal possible.

In Mozambique D. cervina has been collected so far only in the Sofala Province, where it occurs mostly in sand forest and miombo communities, often seen at the forest edge and flying into the open savanna. Adults can be seen between March and May, exhibiting both diurnal (feeding) and nocturnal activity (courtship). Males begin stridulating in flight shortly after the sunset but eventually settle in the tree tops and continue stridulation in the stationary position for several more hours. D. cervina has been seen feeding on leaves of Artabotrys brachypetalus (Annonaceae) and Vitex payos (Verbanceae) , and females have been seen depositing eggs on the latter. Eggs are laid singly on the surface of the leaves, attached with a small stalk ( Fig. 38G ).

Measurements (1 male, 3 females). body w/wings: male 62, female 65–66.1 (65.7.6); body w/o wings: male 34, female 29–33.4 (30.82.3); pronotum: male 7, female 6.3–7 (6.8.4); tegmen: male 49, female 49–52 (50.31.5); hind femur: male 34, female 32–35.7 (33.61.9); ovipositor: 5–5.6 (5.2.3) mm.

Material examined (17 specimens). Tanzania: Usambara— 1 female (holotype) ( ZMBH) ; Mozambique: 1 female ( UEMM) ; Sofala, Coutada 12, Inhamitanga Forest, Camp 1, elev. 210 m (-18.23835, 35.33015), 9–14.iv.2018, coll. P. Naskrecki— 1 female, 1 male ; Coutada 12, Nyago hunting camp, elev. 70 m (-18.660767, 35.455603), 8–16.iv.2016, coll. P. Naskrecki & J. Guyton— 2 males ; Cheringoma, Coutada 12, road to Marromeu , elev. 218 m (- 18.21613, 35.31432), 28.iii.2017, coll. P. Naskrecki— 1 female ; nr. Codzo ( Khodzue ), cave and nearby, elev. 216 m (-18.564, 34.872222), 14–25.iv.2017, coll. P. Naskrecki— 1 male ; Cheringoma, Coutada 12, on road to Inhaminga , elev. 103 m (-18.62409, 35.30772), 17.iv.2016, coll. P. Naskrecki— 1 male ( EOWL) ; GNP, Bela Vista ranger outpost, elev. 26 m (-18.69470, 34.20853), 5–12.v.2015, coll. P. Naskrecki— 2 males ; GNP, Bunga Inselberg, Camp 1, nr. Bunga ranger outpost, elev. 75 m (-18.59989, 34.33686), 21.iv.–5.v.2015, coll. P. Naskrecki— 2 females, 1 male ( MCZ) ; GNP, Chitengo, man-made pond nr. Chikalango , (-18.979878, 34.353419), 15.iii.2017, coll. J. Guyton— 1 female ( EOWL) ; Republic of South Africa:— 1 female (holotype) ( BMNH) ; Zimbabwe: Hot Springs , (-19.65, 32.4666667), 8.iv.1956, coll. G. van Son— 1 female ( TMSA) .

Figures

FIGURE 38. Debrona cervina: A. stridulatory file; B. male abdominal apex, dorsal view; C. female subgenital plate; D. male right wings; E. female, lateral view; F. ovipositor; G. egg; H. male pronotum and stridulatory apparatus, dorsal view.

FIGURE 54. Oscillograms and power spectra of Mozambican Phaneropterinae: A–C. Gonatoxia helleri; D–F. Debrona cervina, stationary call; G–I. Oxyecous lesnei, stationary call; J–L. O. magnus.