Maculambrysus attenuatus (Montandon, 1897) 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 : 211-213

Maculambrysus attenuatus (Montandon, 1897) NEW COMBINATION

( Figs. 6 , 13 )

Ambrysus attenuatus Montandon, 1897a: 15–16 (original description).

Australambrysus attenuatus : Reynoso-Velasco & Sites 2021: 12 (changed combination).

Supplemental description. Pronotum mostly yellow-brown with extensive brown maculation as irregular longitudinal stripes and punctation. Profemur with solid-brown spots and brown punctation dorsally ( Fig. 6A ). Posterior margin of abdominal laterosternite VI unmodified, without tubercle or small projection in posteromedial corner. Posterolateral corners of abdominal terga II–III right angled to rounded, IV–VI spinose ( Fig. 6B ). Abdominal mediosternite VII (subgenital plate) with lateral margins converging posteriorly, without spines or sharp projections at posterolateral angles, and a truncated apex ( Fig. 6C ).

Discussion. Ambrysus attenuatus was described based on a female collected in southeastern Brazil, in the state of Minas Gerais ( Montandon 1897a). The type locality is identified as "Villa Rica, Brésil ", currently referring to the Ouro Preto municipality. De Carlo (1950) recorded this species from Argentina, based on an adult specimen and two nymphs from the province of Misiones. In addition to the new record, De Carlo suggested that the type locality “Villa Rica” is in Paraguay, not in Brazil, as postulated by Montandon (1897a). Nieser et al. (1999) reinforced that the type locality probably refers to Vila Rica (= Ouro Preto), in Minas Gerais.

López-Ruf & Hernández (2007) adopted the criteria proposed by De Carlo (1950), who established Villarrica, in Paraguay, as the type locality for this species. Based on material collected in the provinces of Entre Ríos and Misiones in Argentina, the authors presented a redescription of this species. However, this redescription did not provide detailed information on the morphological features considered relevant for distinguishing species within Ambrysinae . Also, the redescription offered by López-Ruf & Hernández (2007) and the holotype are inconsistent; the authors described the posterolateral angle of abdominal segment III as spinose; however, in the holotype, this angle is right-angled to rounded ( Fig. 6B ). Both De Carlo (1950) and López-Ruf & Hernández (2007) probably did not make direct comparisons between their specimens and the holotype of A. attenuatus . This incongruity suggests a comparative study of Argentine specimens with the holotype is needed to confirm the record of this species in the country.

Regarding the type locality, Montandon (1897a) noted the date and name of the collector in the original description: "1893, Dr. P. Jordan ". The collector in question was probably Paul Jordan, associated with a research center in Děčín in the Czech Republic at that time. Jordan carried out an expedition to Paraguay during 1888– 1889, which included a visit to Villa Rica (= Villarrica) ( Jordan 1893). An annual report of 1893 from the k. k. naturhistorischen Hofmuseum (current NHMW) noted the inclusion of Hemiptera from Paraguay collected by Paul Jordan ( von Hauer 1894). However, there is a possible incongruity in the dates, suggesting that the year 1893 on the label may refer to the deposit of the specimen in the NHMW rather than the date of collection. Thus, it is possible that Montandon (1897a) may have erred regarding the country of origin of the material, since there is no evidence that P. Jordan was in Brazil at that time.

Ambrysus attenuatus was tentatively placed by Reynoso-Velasco & Sites (2021) in Australambrysus , but the authors did not have the opportunity to examine the holotype. However, the holotype has the extensive brown maculation as irregular longitudinal stripes and punctation on the pronotum, and solid brown spots and brown punctation on the forefemur ( Fig. 6A ). The female posterior margin of laterosternite VI is unmodified, without tubercle or small spine in the posteromedial corner. The species of Maculambrysus species share, in addition to these two features, the same shape of the posterolateral corners of abdominal segments III–V, where III is rounded to right-angled, and IV–V are spinose (except M. obscuratus ). Thus, Australambrysus attenuatus is here transferred to Maculambrysus .

The type series must consist only of the female holotype. We examined material from several localities in the state of Minas Gerais in order to identify any females with the same subgenital plate; however, none were found. The posterior margin of the subgenital plate converges posteriorly, without spines or sharp projections in the posterolateral angles, with a truncated apex ( Fig. 6C ), which distinguishes it from all other species of Maculambrysus (see Sites & Reynoso-Velasco 2015 and Sites et al. 2024).

Distribution. Until a comparative study among specimens from Argentina and Brazil is carried out, we consider here only the record from the type locality, in southern Paraguay ( Fig. 13 ).

Published records. Paraguay: Guairá ( Montandon 1897a). The records provided by De Carlo (1950), Souza et López-Ruf & Hernández (2007), and Mazzucconi et al. (2022) are not considered here (see discussion above).

Type material examined. HOLOTYPE ♀, by monotypy ( NHMW), [ PARAGUAY, Guairá], Villa ricca 1893, Dr. P. Jordan / Ambrysus attenuatus Montand type 1896 / Amb. attenuatus Mont. det. Montandon / Holotypus Ambrysus attenuatus Montandon, 1897 Verh. Kk.Zool.Bot.Ges. Wien: 15 des. H. Zettel / NHMW Hemiptera image Coll. 000387 / NHMW-Hemip-Inv.No. 000.023.588 .

Figures

FIGURE 6. Maculambrysus attenuatus (Montandon, 1897) n. comb., female holotype (NHMW), (A) dorsal and (B) ventral habitus, (C) subgenital plate, arrows indicate posterolateral corners of abdominal terga III–IV, (D) holotype labels. Figures © Harald Bruckner / NHMW Hemiptera Image Collection. Size bars = 1 mm.

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.