Pterotiltus biafrensis, sp. nov.
Creators: name: Rowell, C. H. F.
name: Oumarou-Ngoute, Charly
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Orthoptera
Acrididae
Pterotiltus
Pterotiltus biafrensis

description: 18. Pterotiltus biafrensi s sp. nov.
urn:lsid:zoobank.org:act: A5DFC3AE-4F92-4E91-99A0-636A64B39921
Figs 54–55; Table 16
non Pterotiltus miniatulus Karsch, 1893 – Bolívar 1905: 226 (misidentification).
Etymology
The term “Biafra” was used historically by Europeans (including I. Bolívar) for the eastern region of the Gulf of Guinea from E Nigeria (Niger / Cross River delta) to Gabon, including Cabo San Juan).
Type material
Holotype
EQUATORIAL GUINEA • ♂; [Rio Muni], Cabo S. Juan; [1°10′31″ N, 9°20′29″ E]; Aug. 1901; Martínez de la Escalera leg.; MNCN, MNCN_Ent 324769.
Description
Male (Figs 54–55)
Differs only slightly from the generic description, as detailed below.
Small to medium size. Integument rugose and pitted on head, thoracic, and proximal abdominal tergites, but otherwise smooth and shiny.
HEAD. Antennae filiform, longer than head and pronotum together, tapered at their tips. Fastigium of vertex roughly triangular, short, wider than long, sloping forwards, slightly concave, with a weak medial longitudinal depression, containing a pair of minute tubercles just behind the apex; the apex is parabolic and runs smoothly into the frontal ridge. Frons oblique, straight; frontal ridge clearly defined in its upper half with shallow medial sulcus but obliterated in lower half below the medial ocellus. Lateral facial carinae complete but diminish ventrally. Eyes small, almost round, strongly convex; interocular space narrower than antennal scape.
THORAX. Pronotum cylindrical, without carinae; four transverse sulci, the first of which does not extend to the disc. Three deep, wide sulci (i.e., nos 2–4) crossing dorsum, with a large transverse convexity between sulci 3 and 4. Metazona only about one-fifth length of prozona, its posterior margin straight with a slight midline notch, the anterior pronotal margin somewhat produced in the midline, overhanging the occiput. Transverse furrows between meso- and metanota and between metanotum and first abdominal tergite wide and deep. Prosternal process simple, bluntly conical. Mesosternal interspace open, about as wide as long, mesosternal lobes rounded. Metasternal interspace nearly closed. Elytra and wings absent. Hind femur slender, its tip exceeding the end of the abdomen. Lower lobes of the hind knee acutely pointed.
TIBIA. Hind tibia only moderately expanded distally, but its margins are fringed with long hairs; 8 internal and 8 external tibial spines, including apical spines. Arolium large.
ABDOMEN. Tympanum small, almost completely circular. Last abdominal tergite of male with a minute furcula, the paired projections separated by 0.32 mm. Male supra-anal plate widely triangular, very short, not covering completely the paraprocts. Cercus wide at base, laterally compressed, straight in dorsal view, triangular in lateral view, narrowing to a spine-like apex. Male subgenital plate very short, rounded.
PHALLIC COMPLEX. Epiphallus with divided bridge, ancorae absent, lophi short and strong, almost triangular in axial view; small inner lophi present (Fig. 55A); oval sclerites are roughly oval, and not ‘elbowed’ as in miniatulus. Epiphallic membrane contains a ventrolateral sclerite, encircling the ventral half of the ectophallus (Fig. 55B). Phallic dissection was limited, to preserve the unique specimen, and not all details could be completely resolved. Especially, the valvular plate was not dissected off and could not be examined in detail; it is, however, different from that of all other species so far examined, consisting of a circular ‘ruff’ of membrane around the valves (derived from the lateral lobes of the plate) and two flat bars (the medial lobes). Endophallus with a slender flexure, terminating in short spatulate endophallic processes that are appressed to the ventral aedeagal sclerites. The ventral aedeagal sclerites were also left undissected, but their rounded posterior tips project from the edges of the ventral cleft (Fig. 55B).
Female
Unknown.
Colouration
The overall impression is of a yellow and black insect with a green abdomen and green hind legs with red hind knees; front and middle legs dull red. All the black pigmented areas are shiny – unusual in this genus, where black is more often matte. As usual with old museum specimens, it is possible that the currently yellow areas were originally green or even white.
HEAD. Antennal scape and pedicel yellow, flagellum black, with no pale tip. Head predominantly yellow, with black eyestripe. There is a black medial stripe on the occiput, narrowing forwards; mandibles black, clypeus and labrum yellow clouded with black. Palps were probably green in life.
THORAX. Pronotal disc black, except for a yellow patch in the midline extending from the anterior margin to the second sulcus. Lateral pronotal lobes mostly yellow; lower margins of lobes and the pronotal episternum black. Meso- and metathoracic tergites black, weakly blotched dorsally with yellow.
LEGS. Pro- and mesothoracic legs dull red, tarsi blackish red. Hind femur and coxa, yellow (probably green in life), with a wide and diffuse black pregenicular ring, unique in this genus. Hind knee red. Condyle of hind tibia red, shaft of tibia black. Tibial spines reddish black. Tibial spurs, tarsi and claws olive brown, probably green in life.
ABDOMEN. Tergite of first abdominal segment yellow with partial black suffusion. Tergites of abdominal segments 2 & 3 black; abdominal segment 4 to tip of abdomen yellow (probably green in life).
Measurements
See Table 16.
Remarks
This species is known from a single specimen that was erroneously determined by Bolívar (1905) as P. miniatulus (see pp. 92 & 22 above). This specimen, with Bolívar’s original label, is preserved in the Madrid museum (Fig. 54), and we were allowed to examine it and to dissect out its phallus. It is a previously undescribed species of the genus, and not miniatulus. As it is already present in the literature, under an erroneous name, we consider it appropriate to describe it here and give it a specific name, even though it is a unique specimen, and the female is unknown.
Pterotiltus biafrensis sp. nov. differs from the West African P. miniatulus (Bolívar’s determination) in a number of details, especially in colouration, having dark red pro- and meso-thoracic legs and black antennae, and it lacks both the pale blue hind tibiae and the red abdomen seen in the Ghanian and Togoan material of miniatulus. It shows some similarities to P. georgii from Yambata, DR Congo, in having the pro- and meso-thoracic femora red, but the colouration of the hind knee lobes is different, and this Biafran species has black hind tibiae, not pale blue-green ones like georgii. (The two unique specimens (biafrensis & georgii) are of different sexes, which makes comparison more difficult.)
Distribution
So far known only from the coast of Rio Muni (the mainland area of Equatorial Guinea). Cabo San Juan is the SW extremity of the Rio Muni coastline, near the Gabon border. On a modern map it is labelled “Yoni point”, probably an anglophone corruption of the Spanish name.
Status of taxonomic material
Poor. Female unknown, unique holotype, no modern localities. Colouration in life somewhat uncertain, as the unique specimen has been in a museum for over a century.
description: Published as part of Rowell, C. H. F. & Oumarou-Ngoute, Charly, 2025, Review of Pterotiltus Karsch, 1893 (Orthoptera, Acrididae, Oxyinae), pp. 1-104 in European Journal of Taxonomy 986 on pages 92-96, DOI: 10.5852/ejt.2025.986.2853, http://zenodo.org/record/15235428