Hamma nigrum, Durante & Loudit & Susini, 2021

Durante, Antonio, Loudit, Sandrine Mariella Bayendi & Susini, Antonio, 2021, On the genus Hamma Buckton, 1905 (Hemiptera: Auchenorrhyncha) in Equatorial Africa, with descriptions of three new species, European Journal of Taxonomy 748 (1), pp. 89-107 : 94-97

Hamma nigrum sp. nov.

urn:lsid:zoobank.org:act:6A5C5E1E-9D51-41C8-8D1E-75B5C1C458D4

Figs 1 , 4B , 5B

Diagnosis

Species belonging to the genus Hamma with the thorax entirely black and pronotum smooth; suprahumeral horns with a laterally pointing thorn; a posterior process with four nodes, V-shaped in lateral view between the second and fourth nodes; last node roundish in dorsal view, ending in a well-developed terminal spine. Pterostigma about three times as long as broad.

Differential diagnosis

The general black colour clearly distinguishes this species from the following two (i.e., spinellii sp. nov. and caneparii sp. nov.), although not from Hamma heimi . The roughly triangular shape of the supraocular callosity ( Fig. 4B ) is also diagnostic with respect to all other species in the group.

The anchor-like third node ( Fig. 5B ) of the posterior process clearly distinguishes it from all other species in the group, being rhomboidal in dorsal view, whereas it is roughly circular in heimi , and truly anchor-like in spinellii sp. nov. and in caneparii sp. nov.

Other diagnostic characters with respect to spinellii sp. nov. and caneparii sp. nov. include:

– upper margin of the head ( Fig. 4B ) roughly circular (roughly square in spinellii sp. nov. and caneparii sp. nov.);

– metopidium ( Fig. 4B ) smooth (tuberculate in spinellii sp. nov. and caneparii sp. nov.);

– suprahumeral horns ( Fig. 4B ) with a robust thorn slightly curving dorsally in frontal view (straight in spinellii sp. nov. and caneparii sp. nov.);

– pterostigma ( Fig. 5B ) diagnostic only with respect to caneparii sp. nov.: l/w ratio 2.95 in nigrum sp. nov. (mean value); 2.4 in caneparii sp. nov.

Diagnostic characters with respect to heimi include:

– upper margin of the head more arcuate than in heimi ;

– punctation on the pronotum finer than in heimi ;

– first (proximal) node of the posterior process roughly circular in lateral view, dome-shaped in heimi .

Etymology

The species takes its name from the Latin adjective ‛ nigrus ʼ, meaning ‛blackʼ, in the neuter form in accordance with the grammatical gender.

Material examined

Holotype GABON • ♀; Ogooué Ivindo, Mont Sassamongo , Batouala ; 1 Dec. 2012; A. Susini leg.; MSNS.

Paratypes EQUATORIAL GUINEA • 1 ♀; Nyefang , Mossumu ; 5 Oct. 2015; A. Susini leg.; MSNS • 1 ♀; same collection data as for preceding; coll. Susini.

Description

MEASUREMENTS. Holotype total length: 5.2 mm, average total length: 4.5 mm; holotype pronotal length: 5 mm; average pronotal length: 4.7 mm; holotype tegminal length: 4.2 mm, average tegminal length: 4.2 mm.

HEAD. Brilliant black, convex, punctate, with very small and sparse setae; vertex almost twice as wide as high; shallow concavity between the ocelli; upper margin arcuate, rounded, slightly sinuate; ventral margin W-shaped with the lower parts not very pronounced; ocelli clearly above the centro-ocular line. Frontoclypeus pear-shaped, lateral lobes completely fused to frontoclypeus with margins barely distinguishable; rostrum dark brown; antennae light brown.

PRONOTUM. Brilliant black, punctate, almost completely naked; metopidium smooth, almost twice as wide as high, median carina percurrent, unpunctate, straight until the base of the posterior process and subsequently sinuate, supraocular callosities barely noticeable, small and unpunctate, roughly triangular; humeral angles prominent and blunt; suprahumeral horns well developed, with a tower-shaped base (width/height ratio: 1.48), slightly tuberculate, sometimes with dorsal tip reddish-brown, with a robust brown thorn projecting outwards and curving upwards slightly in frontal view. Posterior process brilliant black, punctate, emerging posteriorly from the pronotum and continuously from the posterior margin; sinuate in lateral view, with four nodes, the first of which (proximal) almost spherical; second node small, dome-shaped in lateral view (flattened in dorsal view) with four to eight small spines dorsally; third node anchor-like in dorsal view with one to three spines at the end of the lateral arms; fourth node subspherical, almost twice as big as the first, with many spines and a robust terminal spine at the caudal end; dorsal and ventral carinae discontinuous, black, in some parts tending to brown. A few spines dorsally and ventrally along the trunk of the posterior process between the third and fourth nodes. Each spine bears a very thin light apical seta.

SCUTELLUM ( Fig. 5 ). Entirely black, punctate, with the base longer than the height, emarginate, with scutellar apices acute with a few translucent setae; base swollen except for the corners, with one ogival tubercle on each side of the swelling, each tubercle with a tuft of small whitish setae.

FOREWING. Almost three times as long as wide (l/w ratio 2.94, mean value), hyaline; basally sclerotized, punctate, dark brown-black in colour. Pterostigma sub-triangular with very rounded corners, blackish in colour; venation black to brown; a large sub-pentagonal brown patch extending from costa to inner margin in the median area; a Y-shaped brown patch extending from costa to anal angle, connected with the previous patch at the level of the second discoidal cell.

LEGS. Ochreous yellow, praetarsi brown.

ABDOMEN. Urites black with punctation (in one specimen with white suffusion), and thin brown caudal border.

Figures

Fig. 1. Hamma nigrum sp. nov., holotype, ♀, Gabon, Ogouè Ivindo, Batuala, 1 Dec. 2012, A. Susini leg. (MSNS).

Fig. 4. Morphology. Left suprahumeral horn and left supraocular callosity, frontal view. A. Hamma heimi Boulard, 1968. B. Hamma nigrum sp. nov. C. Hamma spinellii sp. nov. D. Hamma caneparii sp. nov. Figures are not to scale.

Fig. 5. Morphology. Pterostigma of right wing in dorsal view; third node of the posterior process in dorsal view; scutellum in lateral right view. A. Hamma heimi Boulard, 1968. B. Hamma nigrum sp. nov. C. Hamma spinellii sp. nov. D. Hamma caneparii sp. nov. Figures are not to scale.