Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae Ambrysinae). Section 1. Author Reynoso-Velasco, Daniel Instituto de Ecología, A. C. (INECOL), Red de Biodiversidad y Sistemática, Carretera Antigua a Coatepec Núm. 351, El Haya, Xalapa, Veracruz, 91073, MEXICO. Author Sites, Robert W. 0000-0002-3895-813X Enns Entomology Museum, Division of Plant Sciences, University of Missouri, Columbia, Missouri 65211, U. S. A. sitesr @ missouri. edu; https: // orcid. org / 0000 - 0002 - 3895 - 813 X sitesr@missouri.edu text Zootaxa 2022 2022-12-02 5214 3 421 439 journal article 199797 10.11646/zootaxa.5214.3.5 9eef089e-6399-479b-9200-b2e091ccbb12 1175-5326 7389401 B9AD99D4-7061-4280-BFA2-F5339A9B9A55 Ambrysus schuhi Reynoso & Sites ( Figs. 8–9 ) A. schuhi Reynoso-Velasco & Sites 2019a : Zootaxa 4615 (2): 294–297 (original description). Diagnosis. This species can be distinguished from the other three in this section by the female SGP with a pointed apical lobe on the left margin and asymmetrical posterolateral corners; right corner subtriangular, left corner digitate ( Fig. 8B ). Additionally, the male AGP tapers distally to a pointed and laterally directed apex ( Fig. 8C ) and the pseudoparamere posterolateral corners are narrowly rounded ( Fig. 8D ). Comparative notes. At the time of its description, the female SGP of this species was considered similar to that of A. cosmius . Subsequent examination of specimens of A. variegatus has shown that the SGP of A. schuhi is more similar to that of the latter species. Notwithstanding, A. schuhi exhibits the SGP with the left apical lobe well-developed and subtriangular, posterolateral corners asymmetrical, and central lobe with a shallow concavity; whereas A. variegatus exhibits the apical lobe small and rounded, posterolateral corners symmetrical, and the central lobe with a prominent concavity. The overall dorsal appearance of A. schuhi is closer to that of A. variegatus than to A. cosmius . Although at least three more species in the complex present apical lobes on the female SGP, one on each margin, A. schuhi is the sole species with a single and well-developed apical lobe on the left margin. The apical lobe exhibited by A. variegatus is inconspicuous. Discussion. This recently described species measures 11.68–14.04 mm in length and 7.36–8.48 mm in width. In the original description, Reynoso-Velasco & Sites (2019a) suggested a close relationship of A. schuhi and A. cosmius based on the general morphology of the female SGP and the male endosomal sclerites exhibited by both species. This relationship was strongly supported in the recent molecular analysis of the group ( Reynoso-Velasco & Sites 2021 ). Unfortunately, that study did not include A. variegatus , which could be more closely related to A. schuhi than A. cosmius . Variation. No variation was detected in the diagnostic features. Type locality. Mexico : Oaxaca , Mpio. Sta María Zacatepec, El Rosario , 16º51'34.6''N , 97º58'44.7''W . Repository. Female holotype ( Fig. 8A ) is housed at the IEXA. Published records: Mexico : Guerrero , Oaxaca ( Reynoso-Velasco & Sites 2019a ). FIGURE 8. Structures of Ambrysus schuhi Reynoso & Sites. (A) dorsal habitus of female holotype, (B) sternum VI and subgenital plate of female (terminal abdominal segments removed), (C) 6th and 7th abdominal terga of male, (D) 8th abdominal tergum of male, (E) ventral surface of male phallosoma. al = apical lobe. Distribution. Ambrysus schuhi occurs in southern Mexico , in the states of Guerrero and Oaxaca ( Fig. 9 ). The range includes localities below an elevation of 800 meters on the border of the Pacific Lowlands and Sierra Madre del Sur biogeographic provinces. Type material examined. HOLOTYPE ♀ (by original designation). MEXICO : OAXACA : Mpio. Sta. Maria Zacatepec, km 179 carr. Sta. Maria Zacatepec-Putla, El Rosario , Pte. El Rosario , 29-May-2012 , L-1394 / 361 m , 16º51'34.6''N , 97º58'44.7''W , Reynoso-Velasco coll. PARATYPES : same data as holotype ( 3♂ IEXA ; 6♂ , 6♀ UMC); Mpio. Mesones Hidalgo , km 173 carr. Sta. Maria Zacatepec-Putla, Pte. La Junta , 29-May-2012 , L-1395 / 396 m , 16º53'59.7''N 97º58'02''W , Reynoso-Velasco coll. ( 1♂ UMC); Mpio. San Gabriel Mixtepec , Río Rana , km 194 carr. Puerto Escondido-Oaxaca , San Gabriel Mixtepec , L-1380 / 27-May- 2012 , 712 m, 16º06'06.3''N 97º03'52.9''W , Reynoso-Velasco coll. ( 1♂ , 1♀ UMC ); same but 3-Apr-2015 , L-1906, Reynoso-Velasco , Sites , Shepard , & Barr colls., rocks & gravel ( 5♂ , 1♀ IEXA ; 3♂ , 1♀ UMC); [ Mpio. San Gabriel Mixtepec ], San Gabriel Mixtepec , 20- V-84, M. García / Colección del Instituto de Biología , UNAM. México D.F. ( 1♂ CNIN ; 1♂ , 1♀ USNM ); Mpio. Sta. Maria Zacatepec , km 189 carr. Sta. Maria Zacatepec-Putla , S of El Tapanco , L-1393 / 29-May- 2012 , 341 m, 16º47'28.3''N 97º59'20.4''W , Reynoso-Velasco coll. ( 2♂ UMC); Mpio. Sta Maria Zacatepec , Km 201 carr. Mártires de Tacubaya-Santa Maria Zacatepec ca. 13 km NE of San Pedro Amuzgos , L-1391 / 29-May- 2012 , 276 m, 16º42'18.9''N 98º00'52.9''W , Reynoso-Velasco coll. ( 1♂ UMC) . GUERRERO : stream tributary to Laguna Tres Palos, about 22 miles from Acapulco on highway to Mexico City , III:22:1951 R.R. & M. Miller ( 2♂ , 1♀ UMMZ ) .