Isognathotermes severus ( Silvestri, 1914 )

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 : 127-139

Isognathotermes severus ( Silvestri, 1914)

Figs 26–31, 33, 61–63, distribution maps: Figs 45, 49; Table 14

Cubitermes severus Silvestri, 1914: 92–93 , fig. LIV.

Cubitermes severus var. modestior Silvestri, 1914: 93–94 , fig. LV. S yn. nov.

Cubitermes silvestrii Sjöstedt, 1925: 54 . S yn. nov.

Cubitermes severus – Sjöstedt 1926: 250–251. — Snyder 1949: 163. — Krishna et al. 2013: 1936. — Josens & Deligne 2019: 60–61 .

Isognathotermes severus – Hellemans et al. 2021: 233.

Diagnosis

This is the Isognathotermes species with the largest geographic distribution: from Gambia to CAR ( Figs 45, 49).

The worker has a fungifaber EVA but in 12% of the samples examined, it has an EVA intermediate between the fungifaber and finitimus patterns; it is among the medium-sized workers of the genus Isognathotermes ( Fig. 30). Its premolar tooth on left mandible is generally better seen than in most other species.

The soldier is, on average, among the medium-sized soldiers in the genus Isognathotermes ( Figs 21, 28) and its EVA, generally without any crest, looks like a muneris EVA; its head is generally bulbous but this is shared with I. minitabundus and I. ugandensis (and with I. bulbifrons that has a finitimus EVA ).

The imago is, on average, among the middle- to large-sized imagines in the genus Isognathotermes ( Fig. 26).

Confusion may occur mainly with I. fungifaber in West Africa and with I. ugandensis in central Africa. (see discussion about the ambiguities between I. severus and I. ugandensis ugandensis ). This species has been found in various ecosystems (see chorology).

Etymology

The epithet severus means ‘serious, earnest’ in Latin.

Material examined

One hundred fifty-seven samples from 88 locations. Of the 101 old museum samples examined, 42 were initially labelled as Cubitermes severus , two as C. severus var. modestior , one as C. fungifaber , 15 as C. gaigei , six as C. silvestrii , four as C. speciosus , six as C. ugandensis , one as Cubitermes sp. and 24 not identified.

Syntypes of Cubitermes severus Silvestri, 1914

GUINEA • soldier, worker, ♀ (queen); Kakoulima ; 9°46′ N, 13°27′ W; Aug. 1912; F. Silvestri leg.; study code: DJ 0608; initially C. severus ; IEAP • soldier, worker, ♀ (queen); Camayenne ; 9°31.83′ N, 3°41.17′ W; 16 Oct. 1912; F. Silvestri leg.; study code: DJ 0609; initially C. severus ; IEAP • soldier, worker; Kakoulima ; 9°46′ N, 13°27′ W; before 1904; F. Silvestri leg.; study code: DJ 0292; initially C. severus ; AMNH • soldier, worker; Camayenne ; 9°31.8′ N, 13°41.5′ W; 16 Oct. 1912; F. Silvestri leg.; study code: DJ 0293; initially C. severus ; AMNH

Syntypes of Cubitermes severus var. modestior Silvestri, 1914

GUINEA • soldier, worker, ♂ (king); Kindia ; 10°3′ N, 12°52′ W; 20 Aug. 1912; F. Silvestri leg.; study code: DJ 0294; initially C. severus var. modestior ; AMNH • soldier, worker, ♀ (queen); Kindia ; 10°3′ N, 12°52′ W; 20 Aug. 1912; F. Silvestri leg.; study code: DJ 0341; initially C. severus var. modestior ; IEAP .

Krishna et al. (2013: 1927) mention that another subsample is deposited in PPRI (not examined).

Syntypes of Cubitermes silvestrii Sjöstedt, 1925

GUINEA • soldier, worker; Kakoulima ; 9°46′ N; 13°27′ W), Fr. Guinea [= Guinea]; ca 1912; F. Silvestri leg.; study code: DJ 0302; initially C. silvestrii ; AMNH .

Krishna et al. (2013: 1937) mention that another subsample is deposited in NHRM (not examined).

Other material examined

BENIN • soldier, worker; Birni (forêt classée); 10°1′ N, 1°32′ E; Nov. 2016; L.E. Loko leg.; study code: DJ 0402; GenBank no PQ679191 (mitogenome); BE RMCA INS.Iso.059446 • soldier, worker, ♀ (queen); Birni (forêt classée); 10°1′ N, 1°32′ E; Nov. 2016; L.E. Loko leg.; study code: DJ 0403; GenBank nos MN 646735 ( COI), MN 685940 ( COII), MN 686001 ( 28S); BE RMCA INS.Iso.059448 • soldier, worker; Birni (forêt classée); 10°1′ N, 1°32′ E; Nov. 2016; L.E. Loko leg.; study code: DJ 0404; GenBank no PQ679230 (mitogenome); BE RMCA INS.Iso.059445 • soldier, worker; Birni (forêt classée); 10°1′ N, 1°32′ E; Nov. 2016; L.E. Loko leg.; study code: DJ 0405; GenBank no PQ679200 (mitogenome); BE RMCA INS.Iso.059449 • soldier, worker; Birni (forêt classée); 10°1′ N, 1°32′ E; Nov. 2016; L.E. Loko leg.; study code: DJ 0406; GenBank no PQ679221 (mitogenome); BE RMCA INS.Iso.059447 .

BURKINA FASO • soldier, worker; Bama ; 11°21′ N, 4°23′ W; Feb. 2012; S. Traoré leg.; study code: DJ 0052; BE RMCA INS. Iso. 059412 .

CAMEROON • soldier, worker, ♂ (alate); Mont Guendérou ; 7°10′ N, 14°14′ E; before 1914?; Riggenbach leg.; study code: DJ 0324; initially C. silvestrii ; AMNH • soldier, worker, ♀ (alate), ♂ (alate); Ekoua ; 3°52.6′ N, 12°15.5′ E; 28 Mar. 2015; J. Šobotnik leg.; study code: DJ 0249; GenBank no PQ679208 (mitogenome); BE RMCA INS. Iso. 059401 • soldier, worker, ♀ (alate), ♂ (alate); Batié ; 5°17′ N, 10°14.7′ E; 7 Apr. 2015; J. Šobotnik leg.; study code: DJ 0250; BE RMCA INS. Iso. 059402 • soldier, worker, ♀ (alate), ♂ (alate); Koutaba ; 5°39.3′ N, 10°46.4′ E; 8 Apr. 2015; J. Šobotnik leg.; study code: DJ 0251; GenBank no PQ679250 (mitogenome); BE RMCA INS. Iso. 059403 • soldier, worker; Koutaba ; 5°39.3′ N, 10°46.4′ E; 8 Apr. 2015; J. Šobotnik leg.; study code: DJ 0258; GenBank no PQ679229 (mitogenome); BE RMCA INS. Iso. 059407 • soldier, worker, ♀ (alate), ♂ (alate); Boulourou ; 4°48.8′ N, 11°0.1′ E; 10 Apr. 2015; J. Šobotnik leg.; study code: DJ 0252; BE RMCA INS. Iso. 059404 • soldier, worker; Koutaba ; 5°35.988′ N, 10°44.973′ E; 31 May 2017; Y. Roisin leg.; study code: DJ 0530; GenBank no PQ679166 (mitogenome); BE RMCA INS. Iso. 059408 • soldier, worker; Mancha ; 5°33.534′ N, 10°52.836′ E; 1 Jun. 2017; Y. Roisin leg.; study code: DJ 0510; BE RMCA INS. Iso. 059409 • soldier, worker; Koutaba ; 5°35.816′ N, 10°45.856′ E; 2 Jun. 2017; Y. Roisin leg.; study code: DJ 0531; GenBank no PQ679168 (mitogenome); BE RMCA INS. Iso. 059410 • soldier, worker; Kimi ; 6°5′ N, 11°29′ E; 30 Nov. 2023; J. Šobotnik leg.; study code: DJ 0949; GenBank no PV564658 (mitogenome); BE RMCA INS. Iso. 059405 • soldier, worker; Kimi ; 6°5′ N, 11°29′ E; 30 Nov. 2023; J. Šobotnik leg.; study code: DJ 0952; GenBank no PV564651 (mitogenome); BE RMCA INS. Iso. 059406 .

CENTRAL AFRICAN REPUBLIC • soldier; Bouala ; 6°22.8′ N, 15°37′ E; 8 Jan. 1914; Elbert leg.; study code: DJ U006; initially C. severus ; NHMUK 13671956 • soldier, ♀ (alate); Bosoum ; 6°19′ N, 16°22′ E; 1 May 1914; G. Tessmann leg.; study code: DJ U016; initially C. severus ; NHMUK 13671955 • soldier; Boukoko ; 3°54′ N, 17°55′ E; 2 Jul. 1948; P.-P. Grassé and C. Noirot leg.; study code: DJ P187; MNHN EP9939 • soldier; 20 km N of Bangui; 4°37′ N, 18°33′ E; Nov. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P174; MNHN EP9928 • soldier; 20 km N of Bangui; 4°36′ N, 18°31′ E; Nov. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P177; MNHN EP9931 • soldier; Bossembélé ; 5°16′ N, 17°38′ E; 21 Nov. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P175; MNHN EP9929 • soldier; Bossembélé ; 5°16′ N, 17°38′ E; 21 Nov. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P181; MNHN EP9935 • soldier; 70 km from Alindao ; 5°30′ N, 20°49′ E; Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P180; MNHN EP9934 • soldier; 70 km from Alindao ; 5°30′ N, 20°49′ E; Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P184; MNHN EP9938 • soldier; Bambari ; 5°46′ N, 20°40′ E; Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P178; MNHN EP9932 • soldier; Bambari ; 5°46′ N, 20°40′ E; Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P179; MNHN EP9933 • soldier; Bambari ; 5°46′ N, 20°40′ E; Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P182; MNHN EP9936 • soldier; Bambari ; 5°46′ N, 20°40′ E; 4 Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P183; MNHN EP9937 • soldier; Bambari ; 5°46′ N, 20°40′ E; 13 Dec. 1956; P.-P. Grassé and C. Noirot leg.; study code: DJ P176; MNHN EP9930 • soldier; Bambari ; 5°46′ N, 20°40′ E; 1975; P. Eggleton et al. leg.; study code: DJ U070; initially C. ugandensis ; NHMUK 13671994 • soldier; near Bangui; 4°23′ N, 18°34.5′ E; 1975; Becker leg.; study code: DJ U111; initially C. gaigei ; NHMUK 13671894 • soldier, worker, ♂ (alate); Boika ( Mbaïki ); 3°52′ N, 17°58′ E; 11 Apr. 2007; N. Sion leg.; study code: DJ 0934; GenBank no PV564656 (mitogenome); BE RMCA INS. Iso. 059399 • soldier, worker; Mopiti ( Mbaïki ); 3°52′ N, 17°58′ E; 14 Apr. 2007; N. Sion leg.; study code: DJ 0932; GenBank no PV564660 (mitogenome); BE RMCA INS. Iso. 059418 • soldier, worker; Mopiti ( Mbaïki ); 3°52′ N, 17°58′ E; 14 Apr. 2007; N. Sion leg.; study code: DJ 0933; BE RMCA INS. Iso. 059417 • soldier, worker; Bondoé ; 5°10.3′ N, 17°44.2′ E; 23 Apr. 2007; N. Sion leg.; study code: DJ 0004; BE RMCA INS. Iso. 059400 • soldier, worker; Gbasabangui ( Bangui); 4°22.5′ N, 18°34.75′ E; 3 May 2007; N. Sion leg.; study code: DJ 0935; GenBank no PV564646 (mitogenome); BE RMCA INS. Iso. 059452 • soldier, worker; Bondoé ; 5°10.3′ N, 17°44.2′ E; 27 May 2007; N. Sion leg.; study code: DJ 0001; BE RMCA INS. Iso. 059450 • soldier, worker; near Bangui; 4°23′ N, 18°34.5′ E; 30 Oct. 2010; G. Josens leg.; study code: DJ 0367; BE RMCA INS. Iso. 059414 • soldier, worker, ♀ (alate); Mbaïki ; 3°55′ N, 18°0′ E; 24 Apr. 2018; S.P. Wango leg.; study code: DJ 0586; BE RMCA INS. Iso. 059395 • soldier, worker, ♀ (alate); Mbaïki ; 3°55′ N, 18°0′ E; 24 Apr. 2018; S.P. Wango leg.; study code: DJ 0587; GenBank no PQ679223 (mitogenome); BE RMCA INS. Iso. 059388 • soldier, worker; Mbaïki ; 3°55′ N, 18°0′ E; 24 Apr. 2018; S.P. Wango leg.; study code: DJ 0588; BE RMCA INS. Iso. 059394 • soldier, worker; Mbaïki ; 3°55′ N, 18°0′ E; 24 Apr. 2018; S.P. Wango leg.; study code: DJ 0595; BE RMCA INS. Iso. 059389 • soldier, worker; Mbaïki ; 3°55′ N, 18°0′ E; 24 Apr. 2018; S.P. Wango leg.; study code: DJ 0596; GenBank no PQ679247 (mitogenome); BE RMCA INS. Iso. 059396 • soldier, worker, ♀ (alate); Bondoé ; 5°10.3′ N, 17°44.2′ E; 26 Apr. 2018; S.P. Wango leg.; study code: DJ 0589; GenBank nos MN646738 ( COI), MN685943 ( COII), MN686004 ( 28S); BE RMCA INS. Iso. 059393 • soldier, worker, ♀ (alate); Bondoé ; 5°10.3′ N, 17°44.2′ E; 26 Apr. 2018; S.P. Wango leg.; study code: DJ 0590; GenBank no PQ679244 (mitogenome); BE RMCA INS. Iso. 059390 • soldier, worker, ♂ (alate); Bondoé ; 5°10.3′ N, 17°44.2′ E; 26 Apr. 2018; S.P. Wango leg.; study code: DJ 0591; GenBank no PQ679206 (mitogenome); BE RMCA INS. Iso. 059392 • soldier, worker; Bondoé ; 5°10.3′ N, 17°44.2′ E; 26 Apr. 2018; S.P. Wango leg.; study code: DJ 0594; GenBank no PQ679201 (mitogenome); BE RMCA INS. Iso. 059391 • soldier, worker, ♂ (king); Bangui?; 4°21′ N, 18°30′ E; 3 May 2007; N. Sion leg.; study code: DJ 0936; GenBank no PV564647 (mitogenome); BE RMCA INS. Iso. 059398 .

CHAD • soldier, worker; Moundou ; 8°24′ N, 16°24′ E; 23 May 1948; P.-P. Grassé and C. Noirot leg.; study code: DJ 0431; MNHN EP9923 .

CÔTE D’IVOIRE • soldier; 6 km E of Odienné ; 9°30′ N, 7°30′ W; Dec. 1938; P.-P. Grassé leg.; study code: DJ P154; MNHN EP9925 • soldier; 6 km E of Odienné ; 9°30′ N, 7°30′ W; Dec. 1938; P.-P. Grassé leg.; study code: DJ P155; MNHN EP9926 • soldier; Odienné ; 7°15′ N, 7°14′ W; Dec. 1938; P.-P. Grassé leg.; study code: DJ P156; MNHN EP9927 • soldier; Mont Tonkui ; 7°24′ N, 7°9′ W; 18 Mar. 1947; C. Noirot leg.; study code: DJ P338; MNHN EP9953 • soldier; Ferkessédougou ; 9°35′ N, 5°12′ W; 2 Oct. 1947; C. Noirot leg.; study code: DJ P192; MNHN EP9940 • soldier; Bouaké–Mbayakro road; 7°40′ N, 4°54′ W; 8 Oct. 1947; C. Noirot leg.; study code: DJ P332; MNHN EP9947 • soldier, worker; Youhouli ; 5°25′ N, 4°29′ W; 7 Sep. 1953; M. Lüscher leg.; study code: DJ 0330; initially C. severus ; AMNH • soldier; Yapo ; 5°44′ N, 4°5′ W; 26 May 1960; C. Noirot leg.; study code: DJ P323; MNHN EP9861 • soldier, ♀ (alate); Kpouébo ( Orumbo Boka); 6°21′ N, 4°53.7′ W; 30 Oct. 1960; C. Noirot leg.; study code: DJ P346; MNHN • soldier, ♂ (alate); Adiaké ; 5°27′ N, 3°15.5′ W; 15 Apr. 1963; C. Noirot leg.; study code: DJ P349; MNHN • soldier; Dabou ; 5°19′ N, 4°20′ W; 10 Jun. 1964; P. Bodot leg.; study code: DJ U014; initially C. severus ; NHMUK 13671954 • soldier; Dabou ; 5°19′ N, 4°20′ W; 10 Jun. 1964; P. Bodot leg.; study code: DJ U015; initially C. severus ; NHMUK 13671953 • worker; Taï ; 5°52′ N, 7°20′ W; 1970; C. Kerdelhué leg.; study code: DJ 0749; GenBank no PQ679224 (mitogenome); MNHN EP9942 • soldier, worker; Taï ; 5°52′ N, 7°20′ W; 1970; C. Kerdelhué leg.; study code: DJ 0750; GenBank no PQ679242 (mitogenome); MNHN EP9943 • soldier, worker, ♂ (alate); Pakobo ( Lamto research centre); 6°12′ N, 4°59′ W; 8 Mar. 2010; K. Dosso leg.; study code: DJ 0017; BE RMCA INS. Iso. 059385 • soldier, worker; Pakobo ( Lamto research centre); 6°12′ N, 4°59′ W; 8 Mar. 2010; K. Dosso leg.; study code: DJ 0066; BE RMCA INS. Iso. 059386 • soldier, worker; Pakobo ( Lamto research centre); 6°12′ N, 4°59′ W; 8 Mar. 2010; K. Dosso leg.; study code: DJ 0069; BE RMCA INS. Iso. 059387 • soldier, worker, ♀ (alate), ♂ (alate); Korhogo ; 9°24′ N, 5°37′ W; 2013; T. Coulibaly leg.; study code: DJ 0044; BE RMCA INS. Iso. 059411 • soldier; Korhogo ; 9°24′ N, 5°37′ W; 2013; T. Coulibaly leg.; study code: DJ 0056; BE RMCA INS. Iso. 059441 • soldier, worker; Youhouli ; 5°26.433′ N, 4°29.351′ W; 18 Feb. 2015; G. Josens leg.; study code: DJ 0408; BE RMCA INS. Iso. 059439 • soldier, worker; Youhouli ; 5°26.417′ N, 4°29.333′ W; 18 Feb. 2015; G. Josens leg.; study code: DJ 0410; GenBank no PQ679209 (mitogenome); BE RMCA INS. Iso. 059440 • soldier, worker; Pakobo ( Lamto research centre); 6°12.56′ N, 4°58.584′ W; 21 Feb. 2015; G. Josens leg.; study code: DJ 0411; GenBank no PQ679169 (mitogenome); BE RMCA INS. Iso. 059415 • soldier, worker; Taabo ; 6°17.87′ N, 5°0.129′ W; 21 Feb. 2015; G. Josens leg.; study code: DJ 0409; GenBank nos MN646736 ( COI), MN685941 ( COII), MN686002 ( 28S); BE RMCA INS. Iso. 059455 • soldier, worker; Katiola ; 7°58.6′ N, 5°4′ W; 26 Feb. 2015; G. Josens leg.; study code: DJ 0260; BE RMCA INS. Iso. 059413 • soldier, worker; Odienné ; 9°26.252′ N, 7°34.935′ W; 26 Feb. 2015; G. Josens leg.; study code: DJ 0414; BE RMCA INS. Iso. 059444 • soldier, worker, ♀ (queen); Man ; 7°24.7′ N, 7°35.1′ W; 27 Feb. 2015; G. Josens leg.; study code: DJ 0261; BE RMCA INS. Iso. 059416 • soldier, worker, ♂ (king), ♀ (queen); Zéalé ; 5°57.9′ N, 8°11.4′ W; 28 Feb. 2015; G. Josens leg.; study code: DJ 0262; BE RMCA INS. Iso. 059442 • soldier, worker; Zéalé ; 6°57.879′ N, 8°11.386′ W; 28 Feb. 2015; G. Josens leg.; study code: DJ 0415; GenBank no PQ679171 (mitogenome); BE RMCA INS. Iso. 059443 • soldier, worker; Route Man–Duékoué ; 6°50.051′ N, 7°24.53′ W; 1 Mar. 2015; G. Josens leg.; study code: DJ 0413; GenBank nos MN646737 ( COI), MN685942 ( COII), MN686003 ( 28S), PQ679236 (mitogenome); BE RMCA INS. Iso. 059451 .

GABON • soldier; La Lopé N.P.; 0°15′ S, 11°35′ E; 15 Mar. 1998; M. Harry leg.; study code: DJ P251; MNHN EP9945 .

GAMBIA • soldier, ♂ (king); Tabo Kotor ; 13°24′ N, 16°40′ W; 10 Sep. 1966; W.A. Sands leg.; study code: DJ U100; initially C. gaigei ; NHMUK 13671897 • soldier, ♂ (king); Bathurst [= Banjul]– Yundum road; 13°28′ N, 16°38′ W; 12 Sep. 1966; W.A. Sands leg.; study code: DJ U103; initially C. gaigei ; NHMUK 13671898 • soldier; Sanyangh–Gunjur road; 13°15′ N, 16°46′ W; 16 Sep. 1966; W.A. Sands leg.; study code: DJ U108; initially C. gaigei ; NHMUK 13671885 • soldier, worker, ♀ (queen); Bathurst [= Banjul]; 13°13′ N, 16°19′ W; 18 Sep. 1966; W.A Sands leg.; study code: DJ 0717; initially C. gaigei ; NHMUK 13671896 • soldier; Bakau ; 13°28′ N, 16°40′ W; 17 Nov. 1973; R.M.C. Williams and R.W. Lamb leg.; study code: DJ U007; initially C. severus ; NHMUK 13671950 • soldier; Jambanjeli ; 13°17′ N, 16°44′ W; 25 Nov. 1973; R.W. Lamb leg.; study code: DJ U018; initially C. severus ; NHMUK 13671952 • soldier; Abuko game reserve; 13°24′ N, 16°39′ W; 5 Dec. 1973; R.M.C. Williams and R.W. Lamb leg.; study code: DJ U008; initially C. severus ; NHMUK 13671951 • soldier, ♂ (king); Abuko game reserve; 13°24′ N, 16°39′ W; 5 Dec. 1973; R.M.C. Williams and R.W. Lamb leg.; study code: DJ U017; initially C. severus ; NHMUK 13671949 • soldier, worker; Brikama ( Nyambai Forest ?); 13°18′ N, 16°40′ W; 1 Nov. 2013; A. Ndiaye leg.; study code: DJ 0220; BE RMCA INS. Iso. 059397 .

GHANA • soldier, ♀ (queen); Larabanga–Sawla road; 9°13′ N, 1°55′ W; 22 Feb. 1959; W.A. Sands leg.; study code: DJ U115; initially C. gaigei ; NHMUK 13671882 • soldier; Bolgatanga ; 10°34′ N, 0°50′ W; 9 Mar. 1959; W.A. Sands leg.; study code: DJ U030; initially C. severus ; NHMUK 13671966 • soldier; Tumu ; 11°5′ N, 2°17′ W; 16 Mar. 1959; W.A. Sands leg.; study code: DJ U027; initially C. severus ; NHMUK 13671970 • soldier; Lawra ; 10°39′ N, 2°52′ W; 18 Mar. 1959; W.A. Sands leg.; study code: DJ U031; initially C. severus ; NHMUK 13671967 • soldier; Tamale–Yeji road; 8°55′ N, 0°30′ W; 27 Mar. 1959; W.A. Sands leg.; study code: DJ U024; initially C. severus ; NHMUK 13671969 • soldier, ♀ (queen); Akumadan on Wenchi–Kumasi road; 7°28′ N, 1°58′ W; 1 Apr. 1959; W.A. Sands leg.; study code: DJ U101; initially C. gaigei ; NHMUK 13671883 • soldier, ♀ (queen); Akumadan on Wenchi– Kumasi road; 7°28′ N, 1°58′ W; 1 Apr. 1959; W.A. Sands leg.; study code: DJ U102; initially C. gaigei ; NHMUK 13671885 • soldier; Nakpanduri ; 10°34′ N, 0°17′ W; 6 Jun. 1959; W.A. Sands leg.; study code: DJ U023; initially C. severus ; NHMUK 13671968 • soldier; Ejura ; 7°23′ N, 1°22′ W; 20 Oct. 1966; W.A. Sands leg.; study code: DJ U020; initially C. severus ; NHMUK 13671971 • soldier, ♀ (alate); Kumasi–Sunyani ; 6°53′ N, 1°52′ W; 12 Jul 1975; R.M.C. Williams leg.; study code: DJ U116; initially C. gaigei ; NHMUK 13671895 .

GUINEA • ♀ (alate), ♂ (alate); “ La Mé forest ”; 9°31.5′ N, 13°41.1′ W; 31 Jan. 1931; P.-P. Grassé leg.; study code: DJ 0429; initially C. fungifaber in MNHN; MNHN EP9921 • soldier; Camayenne ; 9°31.5′ N, 13°41.1′ W; 1934; P.-P. Grassé leg.; study code: DJ 0427; MNHN EP9920 • soldier, worker, ♀ (queen); Camayenne ; 9°31.5′ N, 13°41.1′ W; 1934; P.-P. Grassé leg.; study code: DJ 0430; MNHN EP9922 • soldier, ♂ (alate); Nzo ; 7°41′ N, 8°19′ W; 25 Mar. 1947; C. Noirot leg.; study code: DJ P322; MNHN EP9924 • soldier, ♀ (alate); Nzo ; 7°41′ N, 8°19′ W; 26 Mar. 1947; C. Noirot leg.; study code: DJ P343; MNHN • soldier, ♀ (queen); Nzo ; 7°41′ N, 8°19′ W; 27 Mar. 1947; C. Noirot leg.; study code: DJ P342; MNHN • soldier; Nimba mountain ; 10°0′ N, 13°0′ W; Apr. 1996; M. Harry leg.; study code: DJ 0751; MNHN EP9944 • soldier; Foulaya ; 10°0′ N, 12°50′ W; 20 Jun. 1996; F.L. Guilavogui leg.; study code: DJ 0068; initially C. severus in RMCA; BE RMCA INS. Iso. 059421 • soldier; Forécariah ; 9°28′ N, 13°6′ W; 21 Jun. 1996; O. Diallo leg.; study code: DJ 0067; initially C. severus in RMCA; BE RMCA INS. Iso. 059420 • soldier, worker; Haut-Niger N.P.; 10°14.43′ N, 10°27.67′ W; 22 Dec. 1996; M. Mei leg.; study code: DJ 0314; initially C. severus ; MURS .

LIBERIA • soldier, ♀ (alate); unknown location; 7°0′ N, 10°0′ W; 12 Feb. 1975; G. Becker leg.; study code: DJ U009; initially C. severus ; NHMUK 13671957 .

NIGERIA • soldier, ♂ (alate); Enugu Township; 6°27′ N, 7°32′ E; 13 Feb. 1955; W.V. Harris leg.; study code: DJ U106; initially C. gaigei ; NHMUK 13671893 • soldier; Kaduna; 10°15′ N, 7°50′ E; 15 Feb. 1957; W.A. Sands leg.; study code: DJ U025; initially C. severus ; NHMUK 13671974 • soldier, ♂ (alate); Kwei Hill, Heipang ; 9°39′ N, 8°50′ E; 29 Mar. 1957; W.A. Sands leg.; study code: DJ U026; initially C. severus ; NHMUK 13671977 • soldier, worker, ♂ (alate); Ropp ; 9°30′ N, 8°55.7′ E; 3 Apr. 1957; W.A. Sands leg.; study code: DJ 0545; initially C. severus ; NHMUK • soldier, ♂ (alate); Bauchi – Gombe road; 10°17′ N, 9°56′ E; 7 May 1957; W.A. Sands leg.; study code: DJ U105; initially C. gaigei ; NHMUK 13671890 • soldier; Donkin ; 8°37′ N, 11°44′ E; 24 May 1957; W.A. Sands leg.; study code: DJ U028; initially C. severus ; NHMUK 13671972 • soldier; Wamba ; 9°31′ N, 8°37′ E; 23 Feb. 1958; W.A. Sands leg.; study code: DJ U022; initially C. severus ; NHMUK 13671973 • soldier, ♂ (alate); Gboko–Otupko road; 7°17′ N, 8°54′ E; 26 Feb. 1958; W.A. Sands leg.; study code: DJ U032; initially C. severus ; NHMUK 13671976 • soldier, ♀ (queen); Kabba – Ondo road; 7°34.75′ N, 5°48′ E; 2 Mar. 1958; W.A. Sands leg.; study code: DJ U107; initially C. gaigei ; NHMUK 13671889 • soldier, ♂ (alate); Enugu – Onitsha road; 6°25′ N, 7°24′ E; 3 Mar. 1958; W.A. Sands leg.; study code: DJ U113; initially C. gaigei ; NHMUK 13671892 • soldier, ♂ (alate); Enugu – Otukpo road; 6°45′ N, 7°28′ E; 5 Mar. 1958; W.A. Sands leg.; study code: DJ U112; initially C. gaigei ; NHMUK 13671891 • soldier, worker; Dekina ; 7°40.25′ N, 6°56′ E; 7 Mar. 1958; W.A. Sands leg.; study code: DJ 0659; initially C. gaigei ; NHMUK 13671993 • soldier, ♀ (alate); Lokoja ; 7°50′ N, 6°33′ E; 10 May 1958; W.A. Sands leg.; study code: DJ U029; initially C. severus ; NHMUK 13671975 • soldier; Mayo Ndaga ; 6°55′ N, 11°27′ E; ca 1975; J.T. Medler leg.; study code: DJ U021; initially C. severus ; NHMUK 13671978 .

SIERRA LEONE • soldier, worker, ♀ (alate); unknown location; 8°0′ N, 12°0′ W; 14 Jun. 1917; P.A. Buxton leg.; study code: DJ 0323; initially C. silvestrii ; AMNH • soldier; Njala ; 8°6′ N, 12°4′ W; 24 Aug. 1930; E. Hargreaves leg.; study code: DJ U019; initially C. severus ; NHMUK 13671979 • soldier, worker; Njala ; 8°10′ N, 12°24′ W; 24 Aug. 1930; E. Hargreaves leg.; study code: DJ 0325; initially C. silvestrii ; AMNH • soldier, worker; Njala ; 8°10′ N, 12°24′ W; 24 Aug. 1930; E. Hargreaves leg.; study code: DJ 0540; initially C. silvestrii ; NHMUK • soldier, worker; Njala ; 8°10′ N, 12°24′ W; Apr. 1936; E. Hargreaves leg.; study code: DJ 0546; initially C. severus ; NHMUK • soldier, worker, ♂ (alate), ♀ (queen); Njala ; 8°10′ N, 12°24′ W; 29 May 1947; F.A. Squire leg.; study code: DJ 0326; initially C. silvestrii ; AMNH • soldier; Freetown airport; 8°37′ N, 13°11′ W; Jan. 1955; W.V. Harris leg.; study code: DJ U011; initially C. severus ; NHMUK 13671960 • soldier; Njala ; 8°6′ N, 12°4′ W; 27 Jan. 1955; W.V. Harris leg.; study code: DJ U013; initially C. severus ; NHMUK 13671964 • soldier; Freetown ; 8°25′ N, 13°13′ W; Feb. 1955; W.V. Harris leg.; study code: DJ U002; initially C. severus ; NHMUK 13671959 • soldier; Freetown ; 8°25′ N, 13°13′ W; Feb. 1955; W.V. Harris leg.; study code: DJ U003; initially C. severus ; NHMUK 13671961 • soldier, worker, ♀ (queen); Freetown ; 8°28′ N, 13°15′ W; 27 May 1956; J.K. Ocloo and R.M.C. Williams leg.; study code: DJ 0544; initially C. severus ; NHMUK • soldier; Freetown ; 8°28′ N, 13°15′ W; 8 Jan. 1958; W. Wilkinson leg.; study code: DJ U005; initially C. severus ; NHMUK 13671965 • soldier; Freetown ; 8°28′ N, 13°15′ W; 8 Jan. 1958; W. Wilkinson leg.; study code: DJ U012; initially C. severus ; NHMUK 13671960 • soldier; “ Bo residential”; 7°57′ N, 11°44′ W; 10 Jan. 1958; W. Wilkinson leg.; study code: DJ U010; initially C. severus ; NHMUK 13671963 • soldier; Makeni ; 8°53′ N, 12°2′ W; 24 Sep. 1966; W.A. Sands leg.; study code: DJ U004; initially C. severus ; NHMUK 13671958 .

TOGO • soldier; Kloto ; 6°57.17′ N, 0°34.21′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ BB01; BE RMCA INS. Iso. 059380 • soldier; Kloto ; 6°57.17′ N, 0°34.21′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ BB02; BE RMCA INS. Iso. 059381 • soldier; Kloto ; 6°57.17′ N, 0°34.21′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ BB03; BE RMCA INS. Iso. 059383 • soldier; Kloto ; 6°57.17′ N, 0°34.21′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ BB04; BE RMCA INS. Iso. 059384 • soldier; Kloto ; 6°57.17′ N, 0°34.21′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ BB05; BE RMCA INS. Iso. 059382 • soldier, worker; Kloto ; 6°57.15′ N, 0°34.2′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ 0635; BE RMCA INS. Iso. 059454 • soldier, worker; Kloto ; 6°57.15′ N, 0°34.2′ E; 8 Dec. 2018; G. Goergen leg.; study code: DJ 0636; BE RMCA INS. Iso. 059453 • soldier; PN Fazao-Malfakassa, Bonako ; 9°10.08′ N, 0°57′ E; 17 Feb 2025; Y. Roisin leg.; study code: DJ Y383; BE RMCA INS. Iso. 059952 • soldier; Route Atakpamé–Badou ; 7°32.4′ N, 1°0′ E; 19 Feb 2025; Y. Roisin leg.; study code: DJ Y381; BE RMCA INS. Iso. 059950 • soldier; Route Atakpamé–Badou ; 7°33.24′ N, 1°0.54′ E; 19 Feb 2025; Y. Roisin leg.; study code: DJ Y382; BE RMCA INS. Iso. 059951 .

Historical review

The first mention of an Isognathotermes species in the literature probably dates back to Smeathman (1781): of two mushroom-shaped nest-building species, “The largest species, the Termes atrox , in its perfect state measures one inch and three-tenths from the extremities of the wings on the one side to the extremities to the other”. As Smeathman collected in Sierra Leone, this dimension (~ 33 mm) is entirely compatible with the wing dimensions of I. severus found in West Africa. However, Smeathman’s material could not be traced even in the early 20 th century ( Sjöstedt 1926: 218) and is therefore considered lost and unavailable for a systematic revision.

Silvestri (1914: 92–93) described this species under the name Cubitermes severus . He provided a description of queen, soldier, and worker together with measurements and figures. In the same paper, he described Cubitermes severus var. modestior (1914: 93–94); he mentioned that the soldiers and imagines are like the typical form (= Cubitermes severus ) but smaller.

Sjöstedt (1926: 250–251) housed C. severus in the sub-family Termitinae and provided a first description of alates. Sjöstedt (1926: 238–239) considered that C. severus var. modestior deserved to be elevated to the species level. He referred to it under the name C. modestior , housed it in the sub-family Termitinae , and included it in a “ glebae -Gruppe” of small Cubitermes species. He also included C. severus in his soldier’s key of Cubitermes species and inserted it in a “ bulbifrons -Gruppe” of species with an upwards humped frons.

Snyder (1949: 163) catalogued C. severus and C. modestior and housed them in the sub-family Termitinae .

Krishna et al. (2013: 1936) housed C. severus and C. modestior in the sub-family Cubitermitinae .

Josens & Deligne (2019: 39–42) placed these species within the fungifaber valve pattern group.

Hellemans et al. (2021: 233) placed these species in the restored genus Isognathotermes .

The small size of I. modestior might suggest a very young colony, but this is excluded with a physogastric queen; this small size could also be the result of environmental conditions. As I. modestior is known from a single nest, without the aid of sequencing (old sample), there is still some doubt as to its status (abnormal sample or distinct species?). On the basis of morphology alone, since the type material of I. modestior ( Silvestri, 1914) is now included among the smallest specimens of I. severus , it is now considered a junior synonym of Isognathotermes severus ( Silvestri, 1914) .

Redescription

Imago

COLOUR. Head capsule: well sclerotised, fresh samples very dark, C6–C8 (but C4–C 6 in long preserved imagines); fontanelle concolorous with head capsule or paler (up to two levels). Postclypeus C6– C7 slightly paler than head capsule. Antennae C4–C6 without any difference between proximal and distal articles. Thorax: pronotum C6–C7 (paler in long preserved samples), as postclypeus, generally somewhat paler than head capsule; meso- and metanotum C4–C7, sometimes somewhat paler than pronotum. Legs C3–C5; tibia usually slightly (one level) darker than femur. Wings hyaline with brown to grey tinge (Cf2–Cf4), anterior veins darker. Abdomen: tergites C5–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 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 with some fine, pale setae, arranged in a medio-longitudinal strip, generally visible at 40 ×, sometimes only at 80 ×. Legs very pilose, furnished (among numerous fine setae) with some stronger setae: 7–12 on the carina of fore coxa and 0–8 on the ventral side of fore coxa; fore trochanter with some strong setae; tibia pilose fore, mid, and hind tibia furnished with 10–30 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 14; Figs 26, 61). Size: the imagines of I. severus are, on average, medium to large sized in the genus Isognathotermes ( Fig. 26). Head capsule: compound eyes round to shortly oval; ocelli shortly to strongly oval, removed from eyes by a distance equal to 0.4–1.3 ocellus small diameter; fontanelle generally a tiny round or elongate marking. Antennae: 16 articles on alate individuals, always shortened by amputation by two to four articles in queens and kings. Labrum: cupola shaped, wider than long. Left mandible with apical tooth on average medium sized in the genus and 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

* Abbreviations: see definitions in Material and methods.

elevated. Fore coxa flanged ventrally resulting in a carina. Wings: R1 fused entirely with costal margin, sclerotised; Rs simple, sclerotised; M and Cu not or weakly sclerotised with 2–4 and 8–13 branches, respectively. Gut (only studied in some cases): enteric valve weakly developed and hardly comparable with workers’ and soldiers’ valves; odd PCs are slightly longer than even PCs. Caecum present as a small amorphous button.

Soldier

COLOUR. Head capsule generally tending towards deep palette (Cd3–Cd6); there is always a gradient from a darker frons to a paler back, smooth and extended in 72% of the samples examined but more abrupt in the remaining 28% giving in some cases the impression that the head capsule is bicolorous (as in Fig. 13). Antennae and labrum concolorous with or one level paler than head capsule. Mandibles dark (C6–C8) generally with an abrupt clearing on their bases (two palette levels) which is generally the same colour as frons. Thorax and legs paler than head capsule (C2–C4). Abdomen grey to red-brown owing to digestive bolus, sometimes 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 always with 5–8 large setae on each lobe. Thorax: pro- and mesonotum with a small number of setae mainly located on margins. Legs: fore coxa bears at least one fine seta and generally 0–3 spines on carina and generally not any spine (rarely 1–2) on ventral side; trochanter generally with some long lined-up setae, sometimes with 6–7 spines; fore, mid, and hind tibia bearing 3, 2, 2 apical spurs and 0, 2, 0 subapical spurs respectively (the latter sometimes weakly developed) and a row of 6–17 strong setae or spines along their shaft. Abdomen: tergites with some large setae, mainly or 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 14; Fig. 62). Size: the soldiers of I. severus are medium sized in the genus Isognathotermes ( Figs 21, 28). Head capsule: always clearly sclerotised; appreciably longer than wide. Dorsal view: lateral sides mostly subparallel always with a narrowing near posterior third or fourth, from antennal sockets sides converge clearly towards bases of mandibles; posterior side regularly rounded or sometimes with a short straight or even concave part in the middle. Upper profile almost always slightly to strongly concave; angle between extended mandibles and frons varies from right to obtuse; frons generally with a sketched or small anterior hump (without any hump in 10% of the samples examined). Gulamentum in ventral view always constricted in its posterior half, with sides of anterior part either roundly convex or forming an acute widening or even a kind of ear on each side. Antennae: 14.5–15 articles). Labrum: always deeply bifurcate and wider than long, with sides varying from lyre-shaped (in 85% of the samples examined) to convex; lobes angular, frequently with fine, whitish or translucent tips; anterior margin concave. Mandibles: sabre-like generally strongly curved; inner edges generally 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. Right mandible equally or slightly more curved than left. Thorax: pronotum sellate, as wide as 54–64% of head width, with generally entire anterior and posterior margins. Fore coxa flanged ventrally resulting in a sharp carina. Gut: enteric valve seating on left side, best seen in ventral view, situated in second half of abdomen. Caecum always rather small, best seen in ventral view, near centre of abdomen, lobed, rarely (in 6% of the samples examined) with a lobe expanded somewhat forward. Arrangement of enteric valve cushions showing trilateral symmetry, the odd cushions being about 16% longer than the even cushions, generally without any crest ( muneris EVA pattern) or with crests very weakly developed.

Worker

COLOUR. Head capsule pale (C1–C3) turning grey in long preserved samples. Antennae: proximal articles pale (C2–C3), distal articles always one to two levels darker (C4–C5). 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 fine, bent setae (visible only at high magnification, 50 × or more). Thorax: nota with some scattered setae. Legs: fore coxa always carinated, bearing one fine seta and furnished with 3–5 spines on carina and 0–4 on ventral side; fore trochanter with 5–8 spines; fore, mid, and hind tibia bearing 3, 2, 2 apical spurs and 0, 2, 0 subapical spurs respectively (the latter sometimes weakly developed) and a row of 6–15 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 14, Fig. 63). Size: the workers of I. severus are, on average, medium sized in the genus Isognathotermes (with large overlapping on several other species: Fig. 30). Head capsule: weakly sclerotised (except mandibles). Antennae of 14 or 14.5 (rarely 15) articles. Labrum: cupola shaped. Left mandible: apical tooth well developed with a sharp tip when fresh; marginal teeth three in number, first marginal tooth well developed but with a blunt tip even when fresh, second marginal tooth faint (visible as an undulated edge and disappearing in worn mandibles), third marginal tooth with a blunt tip; premolar tooth with its proximal end generally (in 70% of the samples examined) well visible; 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 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 sellate, as wide as 57–73% 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 second half of abdomen. Arrangement of enteric valve cushions of the fungifaber pattern with triradial symmetry: the odd PCs, in their downstream part, are rather narrow and bear crests that are generally as high as or higher than they are wide, with long and strong bristles; however, rather frequently (in 11 cases out of 92), including the syntype from Kakoulima (but not the syntype from Camayenne), the EVA is intermediate between the fungifaber and the finitimus patterns; supporting bristles are generally numerous: 15–25 on each side of the odd PCs; secondary cushions are wide at the upstream end, narrowing noticeably downstream with a homogeneous spine scattering. Caecum always rather small, visible in ventral view, near centre of abdomen, generally with two or three (up to five) short lobes, rarely (in 5% of the samples examined) with a lobe expanded forward.

Chorology-ecology

The geographic distribution of I. severus is linked with the Sudanian savanna, the Guinean forest-savanna mosaic, and the northern Congolian forest-savanna mosaic ecoregions. Some samples were also found in evergreen forests in RCI and in southwest CAR and were certified by their mitogenomes.

This species shows an extended repartition from Gambia to CAR. It seems to be in competition with I. fungifaber ( Figs 45, 49, see the general discussion).

Molecular data

Twenty mitogenomes of I. severus are published alongside this work (GenBank accessions: see Supp. file 3 and ‘Material examined’). Despite the disparity in the origin of the samples (from RCI to CAR), mitogenomes exhibit less than 1.2% dissimilarity with each other (Supp. file 4).