Isognathotermes similifinitimus 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 : 139-143

Isognathotermes similifinitimus Josens & Deligne sp. nov.

urn:lsid:zoobank.org:act:

Figs 26–31, 33, 64, distribution map: Fig. 47; Table 15

Diagnosis

The worker has a finitimus EVA and looks a little more like I. finitimus than I. planifrons .

The soldier also looks a little more like I. finitimus than I. planifrons .

The imago, however, clearly looks more like I. planifrons .

The specimens now assigned to I. similifinitimus sp. nov. were first considered to be close to I. planifrons ; besides their mixed morphology, they were found outside the geographic range of I. planifrons .

Isognathotermes similifinitimus sp. nov. is a cryptic species that can be distinguished for sure only with molecular tools: it is therefore possible that some of the samples previously identified as I. finitimus (that could not be sequenced) belong in fact to I. similifinitimus .

In terms of its ecology and chorology, this species is up to now only known from the Congolese forest south of Kisangani, DRC.

Etymology

The name similifinitimus (from the Latin similis, ‘similar’ and finitimus from the species I. finitimus ) refers to the morphology that is like that of I. finitimus .

Material examined

Two complete samples from one location.

Holotype

DEMOCRATIC REPUBLIC OF THE CONGO • soldier; Yoko ; 0°17.62′ N, 25°17.77′ E; 8 Jun. 2010; B. Le Ru leg.; study code: DJ 0744; GenBank no PQ679199 (mitogenome); BE RMCA INS. Iso. 059457.

Paratypes

DEMOCRATIC REPUBLIC OF THE CONGO • soldier, worker, ♀ (queen); same data as for holotype; BE RMCA INS.Iso.059939 .

Other material examined

DEMOCRATIC REPUBLIC OF THE CONGO • soldier, worker, ♂ (king), ♀ (queen); Yoko ; 0°17.62′ N, 25°17.98′ E; 8 Jun. 2010; B. Le Ru leg.; study code: DJ 0745; GenBank no PQ679249 (mitogenome); BE RMCA INS. Iso. 059456 .

Historical review

This species is described here; only two samples are available which may seem too little for describing a new species but both samples are complete (imago, soldier, worker, and mitogenome).

It was discovered by one of us (BLR) in an evergreen forest south of Kisangani, DRC.

Description

Imago

COLOUR. Head capsule: well sclerotised, dark, C6–C7; fontanelle concolorous with head capsule. Postclypeus concolorous with head capsule. Antennae C5–C6 without any difference between proximal and distal articles. Thorax: pronotum C6–C7, concolorous with head capsule; meso- and metanotum C6–C7, as pronotum. Legs C3–C4. Abdomen: tergites C6–C7. Sternites appreciably paler in middle (C3–C4) with both sides darker (C4–C6); posterior sternites darker (C4–C6) than anterior.

SETATION. Head capsule with some prominent setae, mainly near the eyes, and a higher density of shorter, finer setae everywhere. 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 many shorter ones in middle; meso- and metanotum with some fine, pale setae, arranged in a medio-longitudinal strip, visible at 20 ×, with or without two larger setae on metanotum. Legs very pilose, furnished (among numerous fine setae) with some strong setae: 10–15 on the carina of fore coxa and 2 on the ventral side of fore coxa; tibia pilose; fore, mid, and hind tibia furnished with 10–30 strong setae 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 15; Figs 26, 64). Size: the imagines of I. similifinitimus sp. nov. are medium sized in the genus Isognathotermes ; as shown in Fig. 26. Head capsule: compound eyes nearly round; fontanelle a tiny round to elongate marking; ocelli nearly round to oval, removed from eyes by a distance about equal to 0.8–0.9 ocellus small diameter. Labrum: cupola shaped. Left mandible with apical tooth always longer and more prominent than first marginal; marginal teeth three in number but second one only suggested by a slight undulation of edge between first and third marginal teeth; premolar tooth with proximal end 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 longer and more prominent than first marginal; marginal teeth two in number; first marginal tooth well developed with a sharp tip; second marginal tooth smaller and with a blunt tip; 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 flanged ventrally resulting in a sharp carina.

Soldier

COLOUR. Head capsule C4–C6; there is, in one of the two samples, a strong gradient from a darker frons to a paler back (e.g., from C6 to C4) giving the impression that the head capsule is bicolorous (as in Fig. 13). Gulamentum, antennae, and labrum concolorous with head. Mandibles dark (C7–C8) generally with an abrupt clearing on their bases (two palette levels) which is generally the same colour as frons. Thorax, nota C4 and legs paler (C2–C3). Abdomen grey owing to digestive bolus, 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 very fine, bent setae (visible only at high magnification, 50 × or more). Labrum always with 5–6 large setae on each lobe. Thorax: pro- and mesonotum with some setae mainly located on margins. Legs: fore coxa furnished with 1–2 spines on carina and not any one on ventral side; trochanter with some long setae, and 4–5 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 7–15 spines. Abdomen: tergites with some large setae, only on their posterior margins. Sternites with long setae, erect or slightly directed forward, often coloured, and smaller setae directed backwards.

STRUCTURE (measurements in Table 15; Figs 28, 64). Size: the soldiers of I. similifinitimus sp. nov. are medium sized in the genus Isognathotermes ; ( Fig. 28). Head capsule ( Fig. 64): always clearly sclerotised and appreciably longer than wide. Dorsal view: lateral sides mostly subparallel with a slight narrowing near posterior third or fourth; from antennal sockets sides converge clearly towards bases of mandibles. Upper profile clearly concave; frons: flat without any hump. Gulamentum in ventral view always constricted in its posterior half, with sides of anterior part forming a kind of ear on each side. Antennae: of 15 articles. Labrum: deeply bifurcate and wider than long, with sides lyre-shaped; lobes angular, with translucent to whitish tips; anterior margin concave. Mandibles: sabre-like, regularly curved; 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, 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 14 to 18% longer than the even cushions, with humps hardly developed, moreover, the pilosity becoming abruptly very dense shows the place where a hump is expected; 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 (C2–C3). Antennae: proximal articles pale (C2), distal articles two levels darker (C4). Thorax, nota and legs pale (C1–C3). Abdomen grey 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 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 5 spines on carina and 2 on ventral side; fore trochanter with 6–7 spines; fore, mid, and hind tibia bearing 3, 2, 2 apical spurs and 0, 2, 0 subapical spurs respectively and a row of 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 15; Figs 30, 64). Size: the workers of I. similifinitimus sp. nov. are, on average, medium sized in the genus Isognathotermes (but with large overlapping with several other species: Fig. 30). Head capsule weakly sclerotised (except mandibles). Antennae: 14.5 articles. Labrum: cupola shaped. Left mandible: apical tooth well developed 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; premolar tooth with its proximal end hidden under molar prominence; 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 72% 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 numerous: 25–27 on each side of the odd PCs; 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 or four small lobes).

Chorology-ecology

To date, this species is only known from two samples collected in an evergreen forest near Kisangani, DRC, in the northeastern Congolian lowland forests ecoregion ( Fig. 47).

Molecular data

Two mitogenomes of I. similifinitimus sp. nov. are published alongside this work (GenBank accessions: see Supp. file 3 and ‘Material examined’), with a dissimilarity of 1.48% between them, even though they come from the same locality (Supp. file 4). The phylogenetic reconstructions based on full mitogenomes indicated that this species is paraphyletic with respect to I. phallicaecalis sp. nov. ( Fig. 33), to which mitogenomes were up to 1.50% dissimilar. In this case, the separation of the two species is not justified by molecular dissimilarity but by the different types of caeca.