Maculambrysus obscuratus ( Montandon, 1898 ) Rodrigues & Canejo & Sites, 2024

Rodrigues, Higor D. D., Canejo, Rafael P. R. & Sites, Robert W., 2024, New species, new combinations, and morphological notes of South American Ambrysinae (Heteroptera: Naucoridae), Zootaxa 5447 (2), pp. 199-224 : 213-216

Maculambrysus obscuratus ( Montandon, 1898) NEW COMBINATION

( Figs. 7–8 , 13 )

Ambrysus obscuratus Montandon, 1898: 282–284 (original description).

Supplemental description. Male: accessory genitalic process of abdominal tergum VI exceeding posterior margin of segment VII, subrectangular ( Fig. 8C ); medial lobes of abdominal tergum VIII (pseudoparameres) with posteromedial margin oblique, shallowly convex, without notch on posterolateral corner ( Fig. 8D ); phallosoma elongate, convergent in distal third, with acuminate apex ( Fig. 8F ); left ventral lobe reflexed dorsad, longitudinally oriented ( Fig. 8G ); parameres symmetrical, curved anterodorsally, with apex rounded, elongate setae originating on posterior half, extending mesad ( Fig. 8H ). Female: Left abdominal laterosternite VI with a small, digitate production on posteromedial corner, production poorly developed on right side. Mediosternite VII (subgenital plate) with medial convexity and acute posterolateral projections, not reaching posterolateral corner of abdominal tergum VI ( Fig. 8I ).

Discussion. Ambrysus obscuratus was described based on a male collected in Pernambuco, northeastern Brazil ( Montandon 1898). Nieser (1975) examined and redescribed the holotype of this species, in addition to offering a line drawing of the accessory genitalic process of male abdominal tergum VI. The author compared it with Ambrysus stali — currently Maculambrysus stali (La Rivers, 1962) —separating both species essentially by the posterolateral angle of abdominal tergum IV and the accessory genitalic process. Later, Pelli et al. (2006) recorded it from Minas Gerais, however, without offering further details about its morphology. Reynoso-Velasco & Sites (2021) described the genus Maculambrysus and suggested that A. obscuratus may belong to this genus.

Here, we examined photos in different views of the holotype ( Fig. 7 ), which is deposited in the ZMH collection. Comparing material from northern Brazil with photos of the holotype, we identified a male (and a female by association) as A. obscuratus according to the following characteristics: body length 9.0–9.5; extensive brown maculation on the pronotum and fore femur; posterolateral corner of abdominal tergum IV right-angled to acute, not produced posteriorly ( Figs. 7B , 8B ); hemelytra uniformly brown to dark-brown without lighter mottling; propleuron and mesepisternum dark-brown, contrasting with the ventral surface brownish; and the accessory genitalic process of male abdominal tergum VI present and developed (illustrated by Nieser 1975: Fig. 68)—although the shape of the drawing in Nieser (1975) differs slightly from the specimen from Pará. Thus, Ambrysus obscuratus is transferred to the genus Maculambrysus .

Maculambrysus obscuratus is morphologically very similar to M. gallicei Sites , a species recently described from Peru ( Sites 2023b). These two species share: the general body coloration, the posterolateral corner of abdominal tergum IV not spinose, and a similar shape of the male genitalia. However, they can be distinguished by the male parameres and the female subgenital plate. In M. obscuratus , the paramere has an almost straight anterodorsal margin, and the female subgenital plate does not reach the posterolateral angle of abdominal tergum VI, whereas in M. gallicei , the parameres have a sinuous anterodorsal margin and the subgenital plate has the posterior margin and posterolateral corner of tergum VI at the same level. Maculambrysus obscuratus can be distinguished from M. stali by the posterolateral corner of abdominal tergum IV not spinose, and the female left abdominal laterosternite VI with a small, digitate production on the posteromedial corner, whereas in M. stali , the posterolateral corner of abdominal tergum IV is spinose, and the female left abdominal laterosternite VI does not have any digitate production on the posteromedial corner.

Distribution. This species is distributed from the southern region of the Amazon, in the state of Pará, to northeastern Brazil, in the state of Pernambuco ( Fig. 13 ).

Published records. Brazil: Pernambuco ( Montandon 1898) . Pelli et al. (2006) identified this species from the Serra da Canastra , Minas Gerais , in southeastern Brazil. However, they did not provide significant morphological details. Due to the considerable distance between the type locality and Minas Gerais , and the lack of specimens for comparison, this record is not considered valid here. Furthermore, additional undescribed species from Minas Gerais present morphological similarities with M. obscuratus ; thus, we follow a cautious approach with identification of specimens from Minas Gerais.

Type material examined. HOLOTYPE ♂, by monotypy ( ZMH), [ BRAZIL], Pernambuco, Brasilien 5.1.94 / Brasilien Dr. H. Brauns leg. vend. 30.IV.1894, Ambrysus obscuratus Montand. 1898 type A.L. Montandon detm. / Ambrysus obscuratus Montand 1898 type / Type / ZMH 824633.

Additional material examined. BRAZIL, Pará: Jacareacanga, igarapé em floresta, -5.797, -57.402, 19.IV.2013, J.M. Oliveira-Junior col. (1♂ CEIOC); Vitória do Xingu , Caverna Kararaô , igarapé dentro da caverna, -3.140548, -51.817935, 27.XI.2014, E.J. Cunha col. (1♀ CEIOC) .

Figures

FIGURE 7. Maculambrysus obscuratus (Montandon, 1898) n. comb., male holotype (ZMH), (A) dorsal, (B) ventral and (C) lateral habitus, arrow indicates posterolateral corner of abdominal tergum IV, (D) holotype labels. Figures © Thure Dalsgaard / ZMH. Size bars = 1 mm and applies only to Figs. A–B.

FIGURE 8. Maculambrysus obscuratus (Montandon, 1898) n. comb., (A) dorsal and (B) ventral habitus of female from Pará, Brazil (CEIOC), (C) 6th and 7th abdominal terga of male, (D) 8th abdominal tergum of male, (E) genital capsule of male, (F) genital capsule with proctiger removed, (G) ventral surface of phallosoma, arrow indicates left endosomal lobe, (H) parameres, (I) terminal abdominal sterna of female (setae have been removed to reveal shape), arrow indicates small spine of posteromedial corner of left laterosternite VI. Size bars = 1 mm and applies only to Figs. A–B.

FIGURE 13. Distribution records for South American species of Ambrysinae (Naucoridae). Imprecise localities (e.g., only the state is known) are displayed as question marks.