Fusius dilutus Miller, 1957

Liu, Yingqi, Li, Hu & Cai, Wanzhi, 2023, Taxonomic revision of the African assassin bug genus Fusius (Heteroptera: Reduviidae: Peiratinae), European Journal of Taxonomy 910, pp. 25-55 : 29-36

Fusius dilutus Miller, 1957

Figs 1–5

Fusius dilutus Miller, 1957: 62 . Type locality: Calabar [ Nigeria].

Fusius gowdeyi Miller, 1957: 62 . Type locality: Uganda: Luzinga. Syn. nov.

Fusius liberiensis Miller, 1957: 62 . Type locality: Liberia: Sinoe. Syn. nov.

Fusius dilutus anonymus Dispons, 1969: 5 . No locality. Syn. nov.

Fusius dilutus vicinus Dispons, 1969: 5 . Type locality: Tanzania: Pemba. Syn. nov.

Fusius rubricosus – Villiers (nec Stål) 1948: 237, part. — Villiers 1963: 513 (synonymyzation).

Fusius liberiensis – Villiers 1963: 513.

Fusius dilutus dilutus – Dispons 1969: 5. — Maldonado Capriles 1990: 358.

Fusius dilutus gowdeyi – Dispons 1969: 5. — Maldonado Capriles 1990: 358.

Fusius dilutus liberiensis – Dispons 1969: 5. — Maldonado Capriles 1990: 358.

Fusius dilutus anonymus – Maldonado Capriles 1990: 358.

Fusius dilutus vicinus – Maldonado Capriles 1990: 358.

Diagnosis

Body color black and red in large part; anterior lobe of pronotum black, with red stripes thin and obscure, or even only anterior margin of anterior lobe red, posterior lobe of pronotum red; legs brown to blackish brown, apices of coxae, bases of trochanters and apex of fore femur with irregular yellow markings; basal half of dorsal surface of fore tibia and most bases of mid and hind tibiae yellow; apex of clavus yellowish white; fifth abdominal sternite of male with a small process on left side; median pygophore process strongly twisted, knife-shaped in lateral view with apex truncated; apex of right paramere with a small mastoid process; apical margin of dorsal phallothecal sclerite arcuate; process on lower right corner of lateral phallothecal sclerite distinct and round.

Material examined

Holotype

NIGERIA • ♂; “ Holotype; Type; Calabar.; rubricosus Stål ; Distant Coll. 1911 -383; Fusius dilutus sp. n. (holotype) N.C.E. Miller det. 1956”; NHMUK 013586560 ( Fig. 1 ).

Paratypes

CAMEROON • 1 ♀; “ Paratype; Cameroons. Escalera. 1903 -355.; Fusius dilutus sp. n. (paratype) N.C.E. Miller det. 1956”; NHMUK 013586563 .

GABON • 1 ♂; “ Paratype; Gabon 3 1936 Libreville Coll. J. Primot; Fusius dilutus sp. n. (paratype) N.C.E. Miller det. 1956”; K.; NHMUK 013586564 .

NIGERIA • 1 ♂; “ Paratype; Calabar; Distant Coll. 1911 -383; Fusius dilutus sp. n. (paratype) N.C.E. Miller det. 1956”; NHMUK 013586561 • 1 ♀; “ Paratype; Calabar; Distant Coll. 1911 -383; Fusius dilutus sp. n. (paratype) N.C.E. Miller det. 1956”; NHMUK 013586561 ( Fig. 2 ) .

Holotype of Fusius gowdeyi Miller, 1957

UGANDA • ♂; “ Holotype; Type; Uganda Luzinga 17. V. 1916. C.C. Gowdey. 1916-209.; No. 3423; Fusius gowdeyi sp. n. (holotype) N.C.E. Miller det. 1956”; NHMUK 013586565 ( Fig. 3 ).

Paratype of Fusius gowdeyi Miller, 1957

UGANDA • 1 ♀; “ Paratype; Uganda Prot. S. of L. George. 3,200-3,400 ft. 17-19 Oct.1911. S.A. Neave.; 1912-193, Fusius gowdeyi sp. n (paratype) N.C.E. Miller det. 1956”; NHMUK 013586566 .

Holotype of Fusius liberiensis Miller, 1957

LIBERIA • ♂; “ Holotype; Type; Sinoe. Liberia. P.H. Nouman. 1905. 159.; Fusius liberiensis sp. n. (holotype) N.C.E. Miller det. 1956”; NHMUK 013586567 ( Fig. 4 ).

Additional material

KENYA • 1 ♂; “ DR VANSOMEREN MARAGOLI, OCTOBER: 1924; V.G.L. van Someren Collection. Brit. Mus. 1959-468”; NHMUK .

NIGERIA • 1 ♂; “ NIGERIA: lbadan; Moor Plantation . 22. iii. 1956. V.F. Eastop. B.M. 1956-283”; NHMUK .

SIERRA LEONE • 1 ♀; “S. Leone 67 71”; NHMUK .

Redescription

MEASUREMENTS [in mm, ♂ (n = 7), ♀ (n = 4)]. Body length 8.54–9.42 (♂), 9.62–9.65 (♀); maximum width of abdomen 2.90–3.04 (♂), 3.11–3.62 (♀); head length 1.43–1.60 (♂), 1.74–1.76 (♀); length of anteocular part 0.65–0.78 (♂), 0.79–0.82 (♀); length of postocular part 0.42–0.44 (♂), 0.43–0.48 (♀); head width 1.12–1.19 (♂), 1.15–1.20 (♀); eye width in dorsal view 0.21–0.23 (♂), 0.21–0.22 (♀); width of interocular space 0.60–0.69 (♂), 0.69–0.72 (♀); width of interocellar space 0.31–0.35 (♂), 0.35–0.36 (♀); lengths of visible labial segments I:II:III = 0.60–0.61: 0.92–0.93: 0.51–0.55 (♂), 0.62– 0.65: 0.98–0.99: 0.49–0.51 (♀); lengths of antennal segments I:II:III:IV = 0.75–0.79:1.59–1.72:1.11– 1.30:? (♂), 0.78–0.90:1.56–1.58:1.08–1.27:? (♀); length of anterior pronotal lobe 1.50–1.60 (♂), 1.60– 1.79 (♀); length of posterior pronotal lobe 0.85–0.87 (♂), 0.87–0.91 (♀); width of anterior pronotal lobe 2.21–2.24 (♂), 2.30–2.51 (♀); width of posterior pronotal lobe 2.70–2.74 (♂), 2.71–2.97 (♀); scutellum length 1.10–1.12 (♂), 1.36–1.42 (♀); maximum width of scutellum 1.11–1.19 (♂), 1.48–1.52 (♀); hemelytron length 6.70–6.82 (♂), 6.76–7.03 (♀).

COLORATION. Body color black and red in large part ( Figs 1–4 ); head black with labium brown; antenna with scape blackish brown, remaining segments black ( Figs 1–4 ); anterior lobe of pronotum black with red stripes, red stripes thin and obscure ( Figs 3A , 4A ), or even only anterior margin of anterior lobe red ( Figs 1A , 2A ), posterior lobe of pronotum red ( Figs 1A , 2A , 3A , 4A ); scutellum, pleura and sterna black ( Figs 1–4 ); coxae, trochanters and femora blackish brown, apices of coxae, bases of trochanters and apex of fore femur with irregular yellow markings; tibiae dark brown to blackish brown, basal half of dorsal surface of fore tibia and most bases of mid and hind tibiae yellow; tarsi brown ( Figs 1–4 ); base of clavus red, middle part with an oblong black spot, apex yellowish white; corium red with a triangular black spot on area between Cu and Pcu; membrane blackish brown with a yellowish white band crossing two cells, margins of band irregular, apical part of membrane paler ( Figs 1A , 2A , 3A , 4A ); connexivum red with inner part sometimes reddish brown ( Figs 1–4 ); second to seventh abdominal sternites of male yellowish brown ( Fig. 3B ) to blackish brown ( Figs 1B , 4B ), eighth abdominal sternite yellowish brown ( Figs 1B , 3B , 4B ), male genitalia brown ( Fig. 3B ) to blackish brown ( Figs 1B , 4B ); second to sixth abdominal sternites of female yellowish brown to blackish brown, seventh abdominal sternite black with anterior margin yellowish brown, female genitalia brown ( Fig. 2B ).

STRUCTURE. As in generic description. Fifth abdominal sternite of male with a small process on left side ( Figs 1B , 3B , in red circles). This process is not the typical extragenital structure which present on some species of other peiratine genera such as Ectomocoris Mayr, 1865 , Microsandalus Stål, 1866 , Neopirates Miller, 1952 , Peirates Serville, 1831 and Phalantus Stål, 1863 ( Ghauri 1964; Malipatil et al. 2023) as it is located on the fifth abdominal sternite while others are all located on the seventh sternites.

MALE GENITALIA. Median pygophore process strongly twisted ( Fig. 5A–B ), knife-shaped in lateral view with apex truncated ( Fig. 5C ); left paramere ( Fig. 5D ) slightly longer than right paramere ( Fig. 5E ), apex of left paramere truncated ( Fig. 5D ), apex of right paramere with a small mastoid process ( Fig. 5E ); apical margin of dorsal phallothecal sclerite arcuate ( Fig. 5F ); process on lower right corner of lateral phallothecal sclerite distinct and round ( Fig. 5I ). Other structures as in generic description.

Distribution

Nigeria: Calabar, lbadan; Cameroon; Gabon: Libreville; Uganda: Luzinga Village, South of Lake George; Liberia: Sinoe; Kenya: Maragoli; Sierra Leone; Guinea: Mount Nimba ( Villiers 1963); Tanzania: Pemba Island ( Dispons 1969) Zaire [ DR Congo] ( Maldonado Capriles 1990).

Remarks

In the original description, Miller (1957) recorded that all four paratypes of F. dilutus Miller, 1957 are males. However, after examining the type specimens, we found that one paratype from Calabar (NHMUK 013586562) and the paratype from the Cameroons (NHMUK 013586563) are female (see detailed specimen information above).

In his revision of Fusius, Dispons (1969) realized that the characters Miller (1957) used to separate these species were relatively inconspicuous and that some of them were only intraspecific differences. Therefore, F. dilutus , F. gowdeyi Miller, 1957 and F. liberiensis Miller, 1957 were included in one group with the bicolor anterior lobe of the pronotum, the presence of the asymmetrical process on the fifth abdominal sternite and the same type of the male genitalia, and the latter two species were degraded as subspecies of F. dilutus ( Dispons 1969) . Dispons (1969) also described another two subspecies of F. dilutus , F. dilutus vicinus Dispons, 1969 and F. dilutus anonynmus Dispons, 1969 . In the key Dispons (1969) provided, the following characters were used to distinguish the five subspecies of F. dilutus : the anterior lobe of the pronotum with coppery green luster or not, the red area along the anterior margin of the anterior lobe of the pronotum narrow or wide and the pronotal transverse sulcus nearly straight or distinctly angulate medially.

After examining type specimens and other material of these taxa, we found that the coppery green luster may have faded in some dry specimens, for example, the luster is not obvious in holotypes of F. dilutus ( Fig. 1A ) and F. liberiensis ( Fig. 4A ) as Miller (1957) and Dispons (1969) recorded that could be a diagnostic character. The red area along the anterior margin of the anterior lobe of the pronotum could be a character that changes continuously, varying from thin and obscure to distinct and moderately wide. Dispons (1969) recorded that the pronotal transverse sulcus is nearly straight in F. dilutus dilutus and distinctly angulate medially in F. dilutus liberiensis and F. dilutus gowdeyi . However, we observed that the pronotal transverse sulcus of the holotype of F. dilutus ( Fig. 1A ) is also angulate medially, and on the contrary, the pronotal transverse sulcus of the holotype of F. gowdeyi ( Fig. 3A ) seems straighter. So, the shape of the pronotal transverse sulcus is not a stable character to distinguish different subspecies neither. Besides, the presence of the asymmetrical process on the fifth abdominal sternite is indeed observed in all male type specimens of these taxa, which could be a structural diagnosis of F. dilutus .

Moreover, the variations of the characters mentioned above are independent of distribution, and according to the label information and existing literature, the distribution of this species is continuous across central Africa and mainly at low altitude (see Fig. 16 , circular marks). In particular, the type locality of F. dilutus anonymus is unknown ( Dispons 1969), which makes it harder to assign specimens into this subspecies.

To sum up, the morphological and distributional differences of the taxa discussed above are insufficient to classify them into different subspecies. Hence, we regard F. gowdeyi Miller, 1957 , F. liberiensis Miller, 1957 , F. dilutus anonymus Dispons, 1969 , and F. dilutus vicinus Dispons, 1969 as junior subjective synonyms of F. dilutus Miller, 1957 .

Figures

Fig. 1. Fusius dilutus Miller, 1957, holotype, ♂ (NHMUK 013586560) habitus. A. Dorsal view. B. Ventral view. C. Lateral view. Scale bar = 2.00 mm.

Fig. 2. Fusius dilutus Miller, 1957, paratype, ♀ (NHMUK 013586562), habitus. A. Dorsal view. B. Ventral view. C. Lateral view. Scale bar = 2.00 mm.

Fig. 3. Fusius gowdeyi Miller, 1957, holotype, ♂ (NHMUK 013586565), habitus. A. Dorsal view. B. Ventral view. C. Lateral view. Scale bar = 2.00 mm.

Fig. 4. Fusius liberiensis Miller, 1957, holotype, ♂ (NHMUK 013586567), habitus. A. Dorsal view. B. Ventral view. C. Lateral view. Scale bar = 2.00 mm.

Fig. 5. Male genitalia of Fusius dilutus Miller, 1957, non-type specimen from Nigeria (NHMUK). A–C. Pygophore. D. Left paramere. E. Right paramere. F–I. Phallus. A, G. Ventral view. B. Caudal view. C, H, I. Lateral view. D, E. Outer ventrolateral view. F. Dorsal view. Scale bar: A–E = 1.00 mm; F–I = 0.90 mm.

Fig. 16. Distribution of Fusius Stål, 1862.