Ambrysus colimanus Polhemus & Polhemus

Reynoso-Velasco, Daniel & Sites, Robert W., 2025, Revision of the Ambrysus signoreti Stål species complex (Heteroptera: Naucoridae: Ambrysinae). Section 3., Zootaxa 5735 (1), pp. 1-66 : 14-17

Ambrysus colimanus Polhemus & Polhemus

( Figs. 6–8 )

Ambrysus colimanus Polhemus & Polhemus 1981 : Pan-Pac. Ent., 57: 397–399 (original description).

Supplemental description. Female. Mediosternite VII (SGP) asymmetrical; left margin with rounded to pointed lateral lobe at mid-length; right margin with inconspicuous lobe at mid-length; posterolateral corners pointed; central lobe concave medially, giving the appearance of two pointed central lobes, almost at same level as posterolateral corners ( Figs. 6B , 7B ).

Male.Accessory genitalic process of tergum VI (AGP) almost straight and parallel to body axis in basal two thirds, angled to right at approximately 90 degrees at distal third ( Fig. 6C ). Medial lobes of tergum VIII (pseudoparameres) asymmetrical, right pseudoparamere 1.2× wider (at widest point) than left pseudoparamere, posterolateral and posteromesal corners broadly rounded, posterior margin shallowly convex ( Fig. 6D ). Phallosoma elongate, linear, slender, tapering dorsoapically; left endosomal sclerite subtriangular, with transverse row of inconspicuous denticles; right endosomal sclerite small, rounded, lightly sclerotized, inconspicuous, without apparent denticles ( Fig. 6E ). Parameres symmetrical, almost as long as maximum width, mesal margin almost straight. Proctiger almost as long as width at base. Pygophore with elongate setae sparsely distributed over most of surface ( Fig. 6F ), with thick brush of elongate setae on posterior margin (not clearly seen in Fig. 6F as those were unintentionally eliminated during the digital editing of the figure).

Diagnosis. Ambrysus colimanus can be distinguished from other species in this section by the asymmetrical female SGP with a small and rounded lateral lobe on the left margin. Additionally, the pointed posterolateral corners and central lobes are similarly shaped, giving the posterior margin of the SGP the appearance of an upsidedown four-spiked crown ( Fig. 6B ). Also, males exhibit a rounded right endosomal sclerite with no denticles and a subtriangular left endosomal sclerite with a few low denticles ( Fig. 6E ). Furthermore, the small size and contrasting pattern of dark-brown and light-brown on the dorsum ( Fig. 6A ) clearly distinguish this species from others in the complex. The asymmetrically wide pseudoparameres in males of A. colimanus is a unique feature not seen in any other species of the subgenus Ambrysus .

Comparative notes. This is the smallest species in the A. signoreti complex (length ≤ 9.00 mm). The crown shape of the female SGP and asymmetrical pseudoparameres in the males make this species unique among members of the complex. The shape of the male endosomal sclerites is similar to that exhibited by A. brailovskyi and A. cayo . A similar small and rounded right endosomal sclerite is also present in A. inflatus La Rivers (Section 2).

Discussion. This species measures 7.40–9.00 in length and 4.60–5.50 in width. At the time of the description, the authors ( Polhemus & Polhemus 1981) compared this species to A. signoreti Stål , stating that the shape of the SGP was similar between the two species, except for the “flared” lateral lobes present in the latter. Actually, in addition to the lateral lobes, the shape of the posterior margin in both species is distinct from each other. The posterolateral corners and the bilobed central lobe in A. colimanus are particularly similar in shape, whereas the posterolateral corners of A. signoreti are pointed and the lobes of the central lobe clearly rounded. Furthermore, the overall shape of the SGP in A. colimanus is subquadrate, whereas it is subtriangular in A. signoreti . Polhemus and Polhemus (1981) considered the “prominent” maculation in A. colimanus to be similar to that exhibited by A. lunatus Usinger (Section 2). A similar contrasting pattern is exhibited by A. sitesi Reynoso.

In the study on the phylogeny of Cryphocricinae ( Reynoso-Velasco & Sites 2021) , A. colimanus was sister to a clade with seven species, including those with similarly shaped endosomal sclerites (see Comparative notes), whereas the study on the phylogeny of Naucoridae ( Sites 2022) recovered a close relationship of A. colimanus and A. cayo .

Variation. Some females exhibit the SGP with rounded posterolateral corners. Also, some females exhibit a low and rounded lateral lobe on the right margin, giving the impression of an almost symmetrical SGP. The male AGP can be angled at approximately 45 degrees at the distal third. Additionally, some males can present the right endosomal sclerite so lightly sclerotized that it is difficult to distinguish.

Type locality. Mexico: Colima: Mpio Armería, Armería River east of Armería town .

Repository. Male holotype ( Fig. 7A ) is housed at the USNM.

Published records: MEXICO: Colima, Jalisco Michoacán, Nayarit, Oaxaca ( Polhemus & Polhemus 1981; Reynoso-Velasco & Sites 2018a, 2018b, 2019b; Reynoso-Velasco 2021a).

Distribution. Ambrysus colimanus is distributed exclusively in Mexico.Its characteristic neotropical distribution includes the lowlands along the west coast from Nayarit south to Oaxaca ( Fig. 8 ). The species records are in the narrow area of the Pacific Lowlands biogeographic province. The apparent disjunct distribution is due to the lack of collections along the coast in the state of Guerrero.

Type material examined. HOLOTYPE ♂ (by original designation). MEXICO: Colima: [Mpio. Armería], Ameria [Armería] River , [east of Armería Town], 26-XI-1968, CL1229, J. T. Polhemus coll. PARATYPES: same data as holotype ( 1♀ CAS; 1♂ CNIN; 4♂, 3♀ USNM) .

Additional material examined. MEXICO: Colima: Mpio. Armería, Río Armería at Cofradía de Juárez ( Periquillo ), 3 km NE of Armería, 18°57’16.8’’N, 103°56’45.7’’W, 36 m, 24-Jun-2013, L-1571, Reynoso-Velasco coll. ( 2♂, 4♀ CNIN; 5♂, 4♀ IEXA; 17♂, 14♀ UMC) . Jalisco: Arroyo Pueblo Nuevo, trib. of Río Chacala , at approx. 18 mi N of Santiago, 03-III-1955, R. R. Miller & J. T. Greenbank, M 55-45 ( 6♂ UMMZ) ; [Mpio. La Huerta], Cuitzmala, 30-IV-1976, H. Brailovsky / Colección del Instituto de Biología , UNAM, México D.F. ( 1♀ UMC) ; [Mpio. La Huerta], Río Apamila 2 mi NW of La Huerta, 10-Mar-1957, R. R. M. Miller ( 3♂, 1♀ UMMZ) ; [Mpio. La Huerta], Río Cuitzmala , 2.5 km N of Emiliano Zapata, 6-Jan-2005, C.B. Barr ( 1♂, 2♀ EMEC; 1♂ UMC) ; [Mpio. La Huerta], Río Purificación at bridge 2.2 mi W of La Huerta, 20-Feb-1976, R. R. & F.H. Miller & J. T. Greenbank, M 76-32 ( 2♂, 1♀ UMMZ) ; Mpio. Puerto Vallarta, La Desembocada, 20°43’36.5’’N, 105°09’25.7’’W, 39 m, 26-Jun- 2013, L-1577, Reynoso-Velasco coll. ( 1♂, 1♀ UMC) ; Mpio. Puerto Vallarta, Las Palmas , 235 m, 20º49’51.5’’N, 105º05’36.7’’W, 16-Mar-2014, Gómez, J., Smith, S. & Novelo, R. ( 1♂ IEXA) ; Mpio. Puerto Vallarta, Las Palmas de Arriba , 26-Jun-2013, L-1578 / 120 m, 20º49’31.3’’N 105º05’25.3’’W, Reynoso-Velasco coll. ( 1♂, 1♀ UMC) ; Río Cuitzmala SE of Chamela, 6-I-2005, 180’ / William D. Shepard leg. ( 2♂, 1♀ EMEC) . Michoacán: Mpio. Aquila, Aquila, Pte. Ramal Aquila , L-1487, 25-Dec-2012 / 159 m, 18º35’08.1’’N 103º30’51.8’’W, Reynoso-Velasco coll. ( 1♂, 1♀ CNIN; 1♂, 3♀ IEXA; 10♂, 12♀ UMC) ; Mpio. Aquila, El Duín, Río Ostula at Pte. Ostula , 26- Dec-2012, L-1489 / 12 m, 18º27’50.1’’N 103º32’34.1W, Reynoso-Velasco coll. ( 1♂, 1♀ CNIN; 1♂, 2♀ IEXA; 4♂, 9♀ UMC) ; Mpio. Aquila, Santa Cruz de Cachán, Río Coalcomán at Pte. Cachán , L-1491, 26-Dec-2012 / 8 m, 18º15’02.5’’N 103º14’42.2’’W, Reynoso-Velasco coll. ( 2♀ CNIN; 3♂, 2♀ IEXA; 5♂, 25♀ UMC) ; Mpio. Chinicuila, Villa Victoria , 03-Jun-2005, Novelo, R. coll. ( 1♂ IEXA) ; Mpio. Coalcomán, La Chichihua, 10-Jul-2005, R. Novelo & J.A. Gómez colls. ( 2♂ IEXA) ; Mpio. Morelos, La Placita de Morelos, Río Aquila at Pte. La Placita , 26-Dec-2012, L-1488 / 7 m, 18º32’19.9’’N 103º35’17.9’’W, Reynoso-Velasco coll. ( 1♂, 1♀ UMC) . Nayarit: [Mpio. Compostela], El Refilio [Refilión], 2800’, CL729, 8-VI-1975, J. T. Polhemus ( 1♀ USNM) ; [Mpio. San Blas], Mecatán, 5-VIII-84, M. García / Colección del Instituto de Biología , UNAM, México D.F. ( 1♂ UMC) ; 7 mi S of Tepic , 26-VII-1963, Paul J. Spangler / C.J. Drake Accession ( 1♀ USNM) . Oaxaca: Mpio. Mártires de Tacubaya, Mártires de Tacubaya , 29-May-2012, L-1390 / 206 m, 16º34’41.1’’N 98º13’08.7’’W, Reynoso-Velasco coll. ( 3♂, 2♀ 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♀ IEXA; 2♂, 7♀ UMC) ; same but 03-Apr-2015, L-1906, Reynoso-Velasco, Sites, Shepard & Barr colls. ( 1♂, 3♀ UMC) ; Mpio. San Miguel del Puerto, Copalita, Río Copalita at Pte. Copalita , 15°49’12.2’’N, 96°03’57.6’’W, 28 m, 04-Jun-2014, L-1818, Reynoso-Velasco coll. ( 1♂, 2♀ IEXA) ; Mpio. San Pedro Huamelula, Morro Ayutla, Río Ayutla at Pte. Río Ayutla , 15°54’08.7’’N, 95°51’13.3’’W, 29 m, 4-Jun-2014, L-1816, Reynoso-Velasco coll. ( 2♂, 1♀ IEXA) .

Figures

FIGURE 6. Structures of Ambrysus colimanus Polhemus & Polhemus. (A) Dorsal habitus of female, (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 (white scale indicates width of left pseudoparamere), (E) ventral surface of male phallosoma, (F) genital capsule of male (phallosoma removed). pct = proctiger, pr = paramere, pyg = pygophore, res = right endosomal sclerite.

FIGURE 7. Ambrysus colimanus Polhemus & Polhemus. (A) Dorsal habitus and labels of male holotype, (B) subgenital plate and labels of female paratype.

FIGURE 8. Distribution of Ambrysus colimanus Polhemus & Polhemus.