Pterotiltus sobrius, Rowell & Oumarou-Ngoute, 2025

17. Pterotiltus sobrius sp. nov.

urn:lsid:zoobank.org:act:AC29CB9D-95E6-419A-B544-0924D784FB68

Figs 49–53 View Fig View Fig View Fig View Fig View Fig ; Table 15 View Table 15

Etymology

Latin ‘ sobrius ʼ [‘sober, seriousʼ], referring to the absence of bright colours, unusual in this genus.

Type material

Holotype

CAMEROON • ♂; Mefou-et-Akona Division, Ongot Village; 720 m a.s.l.; 10 Feb. 2018. C. Oumarou-Ngoute leg.; MfN 2017253 View Materials .

Paratypes

CAMEROON • 1 ♀; same data as for holotype; MfN 2017252 View Materials • 1 ♂; same data as for holotype; RC 2017254 • 1 ♂; same data as for holotype, but Apr. 2022; MfN 2022814 View Materials • 1 ♂; same data as for preceding; RC 2022815 • 1 ♀; same data as for preceding; RC 2022816 .

Description

Size, medium (males ca 18 mm in length, females ca 23 mm – see Table 15 View Table 15 ). Integument rugose and pitted on head, thoracic, and proximal abdominal tergites, but otherwise smooth and shiny ( Fig. 49 A–B View Fig ).

HEAD. Antennae filiform, longer than head and pronotum together. Fastigium of vertex roughly triangular, short, wider than long, sloping forwards, slightly concave, its surface pitted, sometimes with a weak medial carinula; the obtuse-angular or squared-off apex runs smoothly into the frontal ridge. Frons oblique and straight in profile; frontal ridge clearly defined in its upper half with shallow medial sulcus but obliterated in lower half. Lateral facial carinae well defined dorsally, but obsolete below level of medial ocellus. Eyes small, almost round, strongly convex; interocular space in males equal to, in females slightly wider than, the antennal scape.

THORAX. Pronotum cylindrical, without carinae; three deep, wide sulci crossing dorsum, with large transverse convexities between them that project laterally between sulci 2 & 3. Metazona less than one-fifth length of prozona, its posterior margin almost straight, but slightly concave in the midline, the anterior pronotal margin slightly produced in the midline, overhanging the occiput. Furrows between meso- and metanota and metanotum and first abdominal tergite wide and deep. Prosternal process simple, conical, acute at apex. Mesosternal interspace open, slightly longer than wide, mesosternal lobes rounded. Metasternal interspace nearly closed. Elytra and wings reduced to a minute immoveable cuticular ridge on the mesothoracic pleuron. Hind femur slender. Hind tibia only moderately expanded distally, but densely haired distally; external apical spine present. Arolium large.

ABDOMEN. Tympanum small, circular, open. Last abdominal tergite of male incompletely divided, with a minute furcula ( Fig. 50A View Fig ), the paired projections separated at their tips by 0.55 mm. Male supra-anal plate widely triangular, short, but with a somewhat elongated, more slender, tip, extending halfway across the pallium but not reaching the rim of the subgenital plate. Male cercus wide at base, laterally compressed, triangular in lateral view, narrowing to spine-like apex, slightly incurved. Male subgenital plate very short, rounded, with the dorsal rim slightly thickened.

PHALLIC COMPLEX. Typical of the genus (see generic description and Fig. 1 View Fig ) but has some distinguishing features. Epiphallus with a rather narrow divided bridge, ancorae absent, and a single pair of large lophi, slender, pointed and smoothly curved cephalad throughout their length, not just near their tips ( Fig 50B–C View Fig ); inner lophi absent, but all of the lophal ridge is sclerified, similar to the situation in P. coeruleocephalus . The outer edge of the base of the lophus is produced into a narrow flange, forming a very slight posterior process, something absent in most species of the genus. The ‘oval’ sclerites are roughly triangular in shape ( Fig. 50B View Fig ). Zygoma of the cingulum and arch sclerite fused and produced posteriorly as a valvular plate ( Hollis 1971, 1975) covering the aedeagus dorsally and laterally. Both the medial and the lateral lobes of the plate are complexly formed, with a terminal leaf-shaped medial lobe and flanking concave lateral lobes ( Fig. 51A–B View Fig ). Endophallus with a slender flexure, ending in a short endophallic processes, appressed to ventral aedeagal sclerites of complex shape which form the external ventral valves ( Fig. 52C View Fig ). Epiphallic membrane contains a slender ventrolateral sclerite, encircling the ventral half of the ectophallus ( Figs 51A View Fig , 52A View Fig ). This is only slightly widened anteriorly in the ventral midline, resulting in a very short triangular ventral flange, which is clearly composed of two confluent processes, one from each half of the sclerite.

Female

Supraanal plate more lingulate and less pointed than in male ( Fig. 53C View Fig ). Female cercus robust, laterally flattened, wide basally, tapering to a narrow pointed tip. Paraprocts large and readily visible, extending rearwards as far as the tip of the SAP, with a thickened ventral edge ( Fig. 53B View Fig ). Bursa copulatorix very large, saclike, thinwalled. Spermatheca apparently with only a single ampulla, no lateral diverticulum. Dorsal valves of ovipositor laterally compressed, with obtuse apices; ventral valves smooth, slender, straight, rod-like, sometimes dorsally flattened or slightly grooved. Egg guide prolonged horizontally rearwards between the ventral valves, rather short in comparison with other species of the genus, straight or weakly curved, sharply pointed ( Fig. 53B View Fig ). Ventral surface of female subgenital plate flattish or slightly concave in the midline. The subgenital plate, when dissected free, has an unusual rear margin, with two small incipient projections flanking the egg guide ( Fig. 53A View Fig ). This feature is apparently confined to this species, and may indicate first steps towards the condition seen in Parapterotiltus , where comparable projections are much larger.

Colouration

Male and female are identically coloured ( Fig. 49A–B View Fig ).

HEAD. Antennae dark greenish brown, slightly paler at their tips. Eyes shiny black, drying to brown. Fastigium greenish; occiput and and vertex black. Genae behind eye black, below eye white. Frons white with green mottle. Clypeus and labrum white, but heavily suffused with blue-green and black. External sides of mandibles dark blue green.

THORAX. Pronotum shiny black, with indistinct whitish patches either side of the midline of the disc. The white of the subocular genae continues briefly onto the ventral margins of the lateral pronotal lobes, but is interrupted by extensive black pigmentation between sulci 1 and 3. The posterior ventral angle of the pronotal lobe, behind sulcus 3, is white. Pleura and terga of meso- and metathorax greenish black, with blurred white markings. All legs green, drying to yellow. Hind knee reddish brown dorsally, tibial shaft green proximally, black distally. Hind tarsi greenish black.

ABDOMEN. Abdominal tergites 1 to 3 black, with blurred white patches dorsally. Abdominal 4 dirty white, remainder of abdomen green. The ventral surfaces of thorax and abdomen are blackish green.

Sexual dimorphism

Table 15 View Table 15 gives the ratios of the male to female mean measures. The midline length of the male pronotum (P) is on average 89% that of the female. The overall length of the male body (from fastigium to abdominal tip) is only 82% of the female value. This discrepancy is due to the error in measurement of the male length caused by its upturned genital region. After compensating for the difference in body sizes, the male antennae are significantly longer than those of the female (ratio M/F 1.30) and the male interocular space is significantly smaller (M/F = 0.83).

Measurements

See Table 15 View Table 15 .

Remarks

Pterotiltus sobrius sp. nov. and P. erythroceru s sp. nov. are externally similar in size and colouration, and occasionally are sympatric. They differ externally in the colour of the antennae, and in the brighter red hind knees of erythrocerus . Their phallic characters (epiphalli and valvular plates) are distinctly different.

Distribution

South Cameroon Plateau, from Ongot and Yaoundé. Also recorded from Mamfe, in the Cross River valley North and West of the plateau.

Status of taxonomic material

Adequate. Both sexes known, and modern localities, but the geographical range of the species needs investigation.