Isognathotermes rectimalatus Josens & Deligne, 2025

Josens, Guy, Deligne, Jean, Harry, Myriam, Roy, Virginie, Akama, Pierre D., Coulibaly, Tenon, Dosso, Kanvaly, Goergen, Georg, Hasson, Michel, Kasangij, Patrick Kasangij A, Kifukieto, Carmel, Ru, Bruno Le, Loko, Laura Estelle Yêyinou, Ndiaye, Abdoulaye Baila, Roisin, Yves, Sion, Noémie, Šobotnik, Jan, Stiblik, Petr, Kuenda, Soki Kue Di, Traoré, Saran, Viage, Manuela, Wango, Solange Patricia, Kaymak, Esra, Bourguignon, Thomas & Hellemans, Simon, 2025, An integrative revision of the genus Isognathotermes (Termitidae: Cubitermitinae) with description of seven new species and four new subspecies, European Journal of Taxonomy 1024, pp. 1-197 : 122-127

Isognathotermes rectimalatus Josens & Deligne sp. nov.

urn:lsid:zoobank.org:act:

Figs 26–31, 33, 60, distribution map: Fig. 53; Table 13

Diagnosis

The worker has a finitimus EVA ( Fig. 5) and is among the large-sized workers of the genus Isognathotermes ( Fig. 30) with large-sized enteric valve ( Fig. 31); in particular, the odd PCs elongation index is very high (WVPOdd-Elg = 8.60–11.6).

The soldier is medium sized in the genus Isognathotermes ( Fig. 28) and has almost straight mandibles with a low left mandible apical curvature index (SMlc/SMlL = 0.05–0.07), as in I. minitabundus and I. ugandensis ( Fig. 29) but the latter have a fungifaber EVA.

The only known imago is medium sized, its compound eyes are also medium sized, but they are located far from the head margin and close to the ocelli.

This species is also defined by its ecology and chorology: it has been found only in Angolan woodlands ( Fig. 53).

Etymology

The epithet rectimalatus from the Latin rectus (straight) and malatus (mandible) refers to the straight mandibles of the soldier.

Material examined

Six samples from two locations.

Holotype

ANGOLA • soldier; Mussende ; 10°33.17′ S, 15°39.492′ E; 21 Sep. 2019; M. Hasson leg.; study code: DJ 0719; GenBank no PQ679198 (mitogenome); BE RMCA INS. Iso. 059376.

Paratypes

ANGOLA • soldier, worker; same data as for holotype; BE RMCA INS.Iso.059938 .

Other material examined

ANGOLA • soldier, worker; Mussende ; 10°33.17′ S, 15°39.492′ E; Dec. 2018; M. Hasson leg.; study code: DJ 0771; GenBank no PQ679237 (mitogenome); BE RMCA INS. Iso. 059379 • soldier, worker; Cangandala N.P.; 9°49.33′ S, 16°40′ E; 1 Mar. 2019; M. Viage leg.; study code: DJ 0864; GenBank no PQ679197 (mitogenome); BE RMCA INS. Iso. 059374 • soldier, worker; Cangandala N.P.; 9°49.33′ S, 16°40′ E; 1 Mar. 2019; M. Viage leg.; study code: DJ 0867; GenBank no PQ679203 (mitogenome); BE RMCA INS. Iso. 059375 • worker; Mussende ; 10°33.17′ S, 15°39.492′ E; 13 Aug. 2019; M. Hasson leg.; study code: DJ 0710; GenBank no PQ679233 (mitogenome); BE RMCA INS. Iso. 059377 • soldier, ♂ (alate); Mussende ; 10°33.17′ S, 15°39.492′ E; 25 Oct. 2021; M. Hasson leg.; study code: DJ 0812; BE RMCA INS. Iso. 059378 .

Historical review

The species is described here. It was discovered by two of us (MV & MiH) in the Angolan Miombo.

Description

Imago

The imagines are very similar to those of I. finitimus .

COLOUR. Head capsule: well sclerotised, very dark (C7); fontanelle paler than head capsule. Postclypeus C5, paler than head capsule. Antennae C5. Thorax: pronotum C7 as head capsule; meso- and metanotum C6. Legs C4–C5; tibia slightly (one level) darker than femur. Wings hyaline with brown to grey tinge (Cf3), anterior veins darker. Abdomen: tergites C6. Sternites appreciably paler in middle (C3) with both sides darker (C5); posterior sternites darker (C5) than anterior.

SETATION. Head capsule, with some prominent setae set amongst a high density of short, fine setae forming a dense mat. Labrum and postclypeus with some prominent setae mixed with shorter ones. Antennae with some prominent setae, some more numerous smaller setae and, mainly distally on most articles, a bunch of very fine, bent setae (visible only at high magnification, 50 × or more). Thorax: pronotum with prominent setae mainly on margins and shorter ones in middle; meso- and metanotum without any visible setae, even at 100 ×. Legs very pilose, furnished (among numerous fine setae) with 6 stronger setae on fore coxa and 4–5 on trochanter; tibia pilose fore, mid, and hind tibia furnished with 20–35 spines and bearing 3, 2, 2 apical spurs and 0, 2, 0 subapical spurs, respectively. Abdomen: tergites with many large and small setae. Sternites with long setae, erect or directed slightly forward, and many long and smaller setae directed backwards.

STRUCTURE (measurements in Table 13; Figs 26, 60). Size: the only known imago of I. rectimalatus sp. nov. is among the medium sized of the genus Isognathotermes ( Fig. 26). Head capsule: compound eyes shortly oval; ocelli shortly oval, removed from eyes by a distance about equal to 0.7–0.8 ocellus small diameter; fontanelle generally a tiny round or elongate marking. Antennae: 16 articles on the single known alate. Labrum: cupola shaped. Left mandible apical tooth always more prominent than first marginal; marginal teeth three in number but second one only suggested by an undulation of edge between first and third marginal teeth; only the apical tooth is acute in unworn specimens; premolar tooth with proximal end obscured or partly obscured by molar prominence in dorsal view; molar tooth bearing a rounded molar prominence dorsally and ending posteriorly in a tiny acute apophysis. Right mandible with apical tooth always more prominent than first marginal; marginal teeth two in number; first marginal tooth well developed with a sharp tip when fresh; second marginal tooth smaller and with a blunt tip even when fresh; molar tooth bearing a ventral rounded flange and ending posteriorly in a kind of heel. Thorax: pronotum appreciably wider than long and narrower than head width (including the eyes),

straight to very weakly sellate with anterior lobe short and very slightly elevated. Fore coxa weakly flanged ventrally resulting in an unclear carina. Wings: R1 fused entirely with costal margin, sclerotised; Rs simple, sclerotised; M and Cu not or weakly sclerotised with 3 and 9 branches, respectively.

Soldier

COLOUR. Head capsule C4–C5; frons C5–C6. Gulamentum somewhat darker than head. Antennae and labrum concolorous with head capsule. Mandibles dark (C7–C8) with an abrupt clearing on their bases (two palette levels) which is the same colour as frons. Thorax, nota and legs somewhat paler than head capsule (C3–C4). Abdomen grey to red-brown owing to digestive bolus, rarely with a yellow tinge on tergites.

SETATION. Head capsule with few scattered setae; on frons a dense bunch of setae surrounds and overhangs fontanelle. Antennae with some prominent setae, more numerous smaller setae and at distal extremity of distal articles, a bunch of fine, bent setae (visible only at high magnification, 50 × or more). Labrum with some large setae on lobes. Thorax: pro- and mesonotum with some setae mainly located on margins. Legs: fore coxa furnished with 1–3 spines on carina and 0–1 on ventral side; trochanter with 3–6 long lined-up spines; fore, mid-, and hind tibia bearing 3, 2, 2 apical spurs and 0, 2, 0 subapical spurs respectively; all tibiae furnished with a row of 9–15 spines. Abdomen: tergites with some large setae, mainly on their posterior margins. Sternites with long setae, erect or slightly directed forward, often coloured, and smaller setae directed backwards.

STRUCTURE (measurements in Table 13, Figs 28, 60). Size: the soldiers of I. rectimalatus sp. nov. are medium sized in the genus Isognathotermes ( Fig. 28). Head capsule: clearly sclerotised and appreciably longer than wide. Dorsal view: lateral sides mostly subparallel with a slight narrowing near posterior third; from antennal sockets sides converge clearly towards bases of mandibles; posterior side regularly convex. In profile: upper profile concave; frons: fontanelle overhanged by a sketched frontal hump. Gulamentum in ventral view constricted in its posterior half, with sides of anterior part forming an acute widening with a kind of ear on each side. Antennae of 15 articles. Labrum: deeply bifurcate and wider than long, with sides lyre-shaped; lobes angular or truncated, with fine, whitish or translucent tips; anterior margin concave. Mandibles: sabre-like, almost straight at the base and slightly curved distally; left mandible apical curvature index very low (SMlc/SMlL <0.075); inner edges smooth with one distinct but very small marginal tooth, near molar tooth on each mandible; mandibles clearly shorter than head; entire surface of both mandibles smooth and glossy. Thorax: pronotum sellate, clearly narrower than head, sometimes with a slight notch in anterior margin and entire posterior margin. Fore coxa flanged ventrally resulting in a sharp carina. Gut: enteric valve seating on left side, best seen in ventral view, situated in posterior half of abdomen. Arrangement of enteric valve cushions showing trilateral symmetry: the odd cushions are 19% longer than the even cushions, with humps weakly developed; secondary cushions wide at the upstream end narrowing noticeably downstream with a homogeneous spine scattering. Caecum rather small, best seen in ventral view, near centre of abdomen, lobed (three small lobes).

Worker

COLOUR. Head capsule pale (C1–C3). Antennae: proximal articles pale (C2), distal articles two levels darker (C4). Thorax, nota and legs pale (C1–C3). Abdomen grey to red-brown owing to digestive bolus.

SETATION. Head capsule and postclypeus with few, erect scattered setae. Labrum with few, robust scattered setae. Antennae with some prominent setae, some more numerous smaller setae and at distal extremity of distal articles, a bunch of very fine, bent setae (visible only at high magnification, 50 × or more). Thorax: nota with some scattered setae. Legs: fore coxa carinated, bearing one fine seta and furnished with 2–4 spines on carina and 0–2 on ventral side; fore trochanter with 7–9 spines; fore, mid, and hind tibia bearing 3, 2, 2 apical spurs and 0, 2, 0 subapical spurs respectively and a row of 8–16 spines. Abdomen: tergites with scattered setae. Sternites with long setae, erect or slightly directed forward, often coloured, and smaller setae directed backwards.

STRUCTURE (measurements in Table 13, Figs 30–31, 60). Size: the workers of I. rectimalatus sp. nov. are medium to large sized in the genus Isognathotermes ( Fig. 30). Head capsule weakly sclerotised (except mandibles). Antennae 14–14.5 articles. Labrum: cupola shaped. Left mandible: apical tooth well developed (WMlAmD> 0.19 mm) with a sharp tip when fresh; marginal teeth three in number, first marginal well developed but with a blunt tip even when fresh, second marginal faint (visible as an undulated edge), third marginal with a blunt tip; the premolar tooth is best seen than in most other species; molar tooth bearing a rounded molar prominence dorsally and ending posteriorly in a tiny acute apophysis. Right mandible: apical tooth well developed with a sharp tip when fresh; marginal teeth two in number; first marginal well developed with a sharp tip when fresh; second marginal smaller and with a blunt tip even when fresh; molar tooth bearing a ventral rounded flange and ending posteriorly in a kind of heel. Thorax: pronotum sellate, as wide as 63–70% of head width. Fore coxa flanged ventrally resulting in a sharp carina. Gut: enteric valve seating on left side, best seen in ventral view, situated in posterior half of abdomen. Arrangement of enteric valve cushions of the finitimus pattern with triradial symmetry: the odd PCs, in their downstream part, are wide and bear at that place a very high density of rather short bristles on a globular bulge; supporting bristles are generally numerous: 25–33 on each side of the odd PCs; worker’s valve very large (WVP-AvL> 0.72 mm, Fig. 31) odd PCs elongation index very high (WVPOdd-Elg> 8.5); secondary cushions are wide at the upstream end, narrowing noticeably downstream with a homogeneous spine scattering. Caecum rather small, visible in ventral view, near centre of abdomen, shortly lobed (three small lobes).

Chorology-ecology

This species is only known from Angola; its geographic distribution is linked with the Angolan Miombo woodland ecoregion ( Fig. 53).

Molecular data

The five mitogenomes of I. rectimalatus sp. nov. exhibited less than 2% dissimilarity with each other (Supp. file 4: GenBank accessions: see supplementary Supp. file 3 and ‘Material examined’). After I. acristatus sp. nov., the species I. rectimalatus sp. nov. was established as sister to all remaining Isognathotermes members ( Fig. 33).