Cassida altiuscula Spaeth, 1916

Borowiec, Lech & Świętojańska, Jolanta, 2022, A monograph of the Afrotropical Cassidinae (Coleoptera: Chrysomelidae). Part 6. Revision of the tribe Cassidini 3, the genus Cassida L., Zootaxa 5171 (1), pp. 1-250 : 24-26

Cassida altiuscula Spaeth, 1916

( figs. 2 , 51–53 )

Cassida altiuscula Spaeth, 1916: 48 ; Nummelin & Borowiec, 1991: 14; Borowiec, 1999: 236.

Description. L: 7.50–8.20 mm, W: 5.75–6.20 mm, Lp: 2.60–2.80 mm, Wp: 4.65–5.00 mm, L/W: 1.25–1.41, Wp/ Lp: 1.75–1.83. Body widest in subhumeral part then converging posterad, oval to elongate–oval ( figs. 51, 52 ).

Pronotum black, only area above head yellow to reddish. Scutellum and elytra black, only extreme margins of elytra reddish to brown ( figs. 51–53 ). Head, ventrites and legs yellow to reddish. Antennal segment 1–5 reddish, segments 7–11 dark brown to black, segment 6 from uniformly reddish to partly infuscate.

Pronotum regularly elliptical, with maximum width in the middle, anterior margin regularly convex, sides very broadly rounded, no basal corners. Surface of disc shiny, impunctate, base in front of scutellum with two short longitudinal impressions. Explanate margin distinctly bordered from disc by impression, broad, shiny, impunctate but with few radial impressions, only pale area above head transparent with well visible honeycomb structure.

Base of elytra much wider than base of pronotum, humeral angles strongly protruding anterad, angulate to almost acute. Disc strongly convex with high but obtuse postscutellar tubercle ( fig. 53 ), entire surface with longitudinal and transverse folds, the highest on slope, elytral disc behind humeri distinctly impressed. Punctation moderately coarse, tends to form regular rows but the regularity interrupted by elevated elytral sculpture, only between humeral callus and folds on slope runs regular one or two rows, interspaces shiny. Marginal row distinct, its punctures twice coarser than punctation in central and lateral parts of disc. Intervals mostly indistinctly marked except almost complete submarginal one, marginal interval slightly narrower than submarginal one interrupted by few high folds. Explanate margin narrow, moderately declivous, in the widest part five times narrower than disc, surface irregular with mixed wrinkles and punctation but shiny interspaces, not transparent, honeycomb structure not visible.

Eyes large, gena as long as last palpomere. Clypeus very broad, approximately 1.6 times as wide as long. Clypeal grooves fine but well marked, converging in arc, clypeal plate strongly convex, shiny, with few small setose punctures. Labrum without median emargination, only anterior margin very broadly and shallowly emarginate. Antennae stout, segments 9–10 slightly transverse. Length ratio of antennal segments: 100:57:74:74:72:57:63:61:6 1:59:117. Segment 3 approximately 1.3 times as long as segment 2 and approximately as long as segment 4.

Prosternum moderately broad in the middle, strongly expanded apically, between coxae without special structure but densely pubescent, expanded apex in the middle tuberculate, on sides deeply impressed with several long setae.

Claws simple but with distinctly widened base.

Distribution. Central Africa from Cameroon to Rwanda ( fig. 2 ).

Remarks. A member of the Cassida tosta species–group. It differs from all species of the group in pronotal disc and entire elytra completely black ( figs. 51–53 ). Only the darkest forms of Cassida tosta and C. overlaeti have similar colouration (figs. 54, 62) but C. tosta differs in explanate margin of pronotum completely black ( fig. 62 ) while in C. altiuscula anterior part of the explanate margin is yellow to reddish ( figs. 51, 52 ), and C. overlaeti differs in very low postscutellar elevation (fig. 56) and elytral sides rounded, slightly converging posterad (fig. 54). Cassida altiuscula differs also from all members of this group in the highest elytral hump, elytral sides distinctly converging posterad, and base of elytra the widest compared to the pronotum than any other species of the group.

Type examined. Holotype: [ DEMOCRATIC REPUBLIC OF CONGO (ZAIRE)]: Beni Forest , IX–X 1910, 1, Grauer ( MM).

Other specimens examined. CAMEROON: Efulen , 8 VIII 1910, 1, H.L. Weber ( MNHW) ; Nkolbison , Dept. Nyong–Sanaga, IX 1963, 1 ( MNHW) ; Nkolbison , Yaounde–Bi, 20 V 1963, 1, L. Segers ( ZSM) .

DEMOCRATIC REPUBLIC OF CONGO (ZAIRE): Albert Nat. Park , L. 2265, 1, P. Jolivet ( MRAC) ; Kasai , Forêt de Luebo, 3, M. Babault ( MRAC, MM) ; Mombati , 31 VIII 1927, 1, 2 IX 1927, 1, A. Collart ( IRSN, MM) ; Ubangi , Nzali, 3–4 II 1932, 1, H.J. Bredo ( MNHW) ; Yangambi , 1, M. Perrand ( MRAC) , 1933, 1, Van Laer ( MNHW) , 1948, 1, M. Capon ( MRAC) , 14–15 XII 1952, 3, P. Basilevsky ( MRAC) , 1953, 2, R. Mayné ( MRAC) ; Yangambi , IV 1964, 1, M. Pavan ( MZSNV) .

EQUATORIAL GUINEA: Benito , 1–15 VIII 1906, 1, G. Tessmann ( ZMHU); Nkolentangan, XI 1907 – V 1908, 2, G. Tessmann ( ZMHU, MNHW) .

GABON: Gabun, 1 ( MM).

RWANDA: Karegera , 1700 m, X 1993, 1, T. Wagner ( TW); Nyakabuye, 15–20 VIII 1985, 1, H. Mühle ( HK).

Figures

FIGURE 2. Distribution of Cassida altiuscula (black circles), Cassida blanda (black square) and Cassida procurva (black diamond).

FIGURES 51–53. Cassida altiuscula. FIGURES 54–56. Cassida overlaeti. 51–52, 54–55. Dorsal; 53, 56. Lateral.

FIGURES 57–62. Cassida tosta. 57–58, 60–62. Dorsal; 59. Lateral.