Apiomerus maya, Dispons, 1971

Masonick, Paul & Weirauch, Christiane, 2022, Taxonomic revision of the Apiomerus maya species group (Heteroptera: Reduviidae: Harpactorinae), Zootaxa 5154 (5), pp. 537-556 : 539-541

Apiomerus maya species group

Figs 1–5

Diagnosis: Males are recognized from other species of Apiomerus by a combination of an arrow-shaped dorsal phallothecal sclerite, a pair of enlarged basal dorsolateral sclerites of the endosoma, and longitudinal rows of peglike denticles (between 26–40 in total) on the dorsal surface of the endosoma. Also, the medial process of the pygophore is wide and its base indistinct, giving the appearance of the rami being inserted directly on the posterior margin of the pygophore. Both sexes are predominately black (or dark brown) with reddish-brown antennae and white or pale-yellow markings on the corial veins, thoracic venter, and connexiva.

Description: Male: Macropterous, body elongate ovoid, 11.5–17 mm in length. COLORATION: Body overall predominantly black; antenna reddish-brown; anterior pronotal lobe black or dark brown; posterior pronotal lobe and lateral surfaces of the legs variable, often dark brown; venter of neck, margins of prosternal stridulatory groove, anterior coxal cavities, mesal surface of forecoxa, fore- and mid trochanter and femur, corial veins (partially or completely), anterior portion of connexiva 2–7, area around of abdominal spiracles 2–7, and pair of spots on venter of pygophore white to pale yellow (or tan in some older specimens); membrane of hemelytra either entirely brown or bicolored with basal portion darkened and distal portion hyaline. VESTITURE: integument generally densely setose; head with long thin black or white setae; pronotum, scutellum, corium, and pleura covered with short thick white setae interspersed with longer, less conspicuous black setae; fore and mid legs densely setose, hind tibia more sparsely covered and with a short metatibial comb; abdominal venter sparsely covered with long shiny setae; medial process of pygophore with dense patch of long black setae; mesal surface of paramere covered with short fine setae, apex with long erect setae. STRUCTURE: HEAD: longer than wide, elongate ovoid, anteocular and postocular region subequal in length, latter slightly convex in dorsal view; clypeus slender in dorsal view and apically blunt; labrum short and triangular; eye globular and weakly reniform in dorsal and lateral views, respectively; interocular sulcus deep and strongly curved; ocellus large, located on distinct tubercle, distance between ocelli greater than between anterior margin of ocellus and eye; antennifer near eye, short, and unarmed. Antenna: long, surpassing posterior margin of pronotum; scapus surpassing clypeus; pedicel subequal in length and diameter to scapus; basiflagellomere longer than distiflagellomere, diameters of both same as pedicel. Labium: segment 2 (first visible) short and stout, not reaching anterior margin of eye; segment 3 long and straight, reaching anterior margin of prosternum; segment 4 short and laterally compressed in cross section, reaching roughly to the middle of the stridulatory groove. THORAX: anterior pronotal lobe with rounded lateral margins, shorter and narrower than posterior lobe, vertex deeply sculpted with crescent-shaped furrow; longitudinal sulcus distinct, almost reaching anterior margin; posterior pronotal lobe smooth, disc slightly convex, humeral angle located anteriorly to posterior margin of pronotum, rounded, and the lateral margin of which forming an angle of roughly 90°; posterolateral margin of posterior pronotal lobe strongly keeled; scutellum triangular, margins rounded. Legs: coxa short and globular; trochanter subtriangular; femora cylindrical; fore- and mid tibiae thickened apically; foretarsus with two tarsomeres; mid and hind tarsus with three tarsomeres. Hemelytron: exceeding tip of abdomen by less than 1/4 of its length, corium well developed and leathery. ABDOMEN: strongly convex ventrally; connexivum expanded laterally beyond margin of hemelytron, abdominal sternites distinct. GENITALIA: base of the medial process of the pygophore wide and indistinct, rami inserted on posterior margin of pygophore, nearly vertical in lateral or caudal views; paramere thickened from base to 2/3 its length then weakly or strongly bent mesad, point of insertion is at the apical third of the pygophore, slightly hooked apically; inner margin of genital capsule (exterior rim of pygophore) with small protuberance; anterior opening of pygophore with smooth rim; tergite 9 divided into flat lateral sclerites and a medial membranous area; aedeagus elongate when inflated, with articulatory apparatus broad and triangular; dorsal phallothecal sclerite heavily sclerotized and arrow-shaped (with the exception of A. immundus which is subconical), apex reflexed and either slightly or deeply notched; phallosoma weakly sclerotized laterally and with transverse striations; endosoma with a pair of elongated basal dorsolateral sclerites, either flat or twisted apically; endosoma membranous and lightly striated; dorsal surface of endosoma with longitudinal rows of peg-like denticles (between 20–40 in total);

Female: Larger than male, 11.5–19 mm in length, similar to male except for the following: COLORATION: usually lacking conspicuous white or pale-yellow markings on the mesal surfaces of the fore- and mid femur and lateral spots on abdominal sterna 3–5. VESTITURE: metatibial comb much longer than that of male; abdominal venter densely covered with stiff shiny setae. STRUCTURE: ABDOMEN: lateral margins of tergite 8 rounded and not produced as deflexed lobes. GENITALIA: syntergite 9/10 roughly trapezoidal, lateral margins rounded; gonocoxa 8 large, L-shaped to roughly quadrangular, posterior margin lined with 20-30 very short, stout setae; gonoplac mitten-shaped, lightly fused medially, each side bearing a thumb-like dorsal medial projection topped with roughly two setae, and a strongly sclerotized posteriorly projecting lobe covered with many setae.

Discussion: In these taxa, the base of the medial process is greatly reduced giving the impression of the rami being inserted directly on the posterior rim of the pygophore ( Fig. 2A–F ). The rami are often broadly spaced from one another and render the medial process either V-shaped, as frequently observed in A. pipil (see Fig. 2C ), or lyreshaped (most male A. venosus , Fig. 2E–F ). Other than using coloration, females in this group are best diagnosed through association with males as their genital morphology appears to be less variable at the species-level.

Identification key to the Apiomerus maya species group

1 Small species (11.5–12.5 mm), body and hemelytra predominantly dark brown, males with basal dorsolateral sclerites of the endosoma short to moderate in length, broad, flat, and round or oblong.......................................... 2

- Medium to large species (14–19 mm), body and hemelytra variable in color (brown or black with light-colored markings on connexiva and corium, distal portion of membrane of hemelytra sometimes hyaline), males with basal dorsolateral sclerites of the endosoma elongate, often slightly twisted apically, and paddle-shaped........................................ 3

2 Dorsal phallothecal sclerite of males without a pair of prominent triangular projections at its base, basal dorsolateral sclerites of the endosoma of moderate length, oblong, and with fine sculpturing ( Fig. 3A ).......... A. immundus Bergroth, 1898

- Dorsal phallothecal sclerite of males with a pair of prominent triangular projections at its base ( Figs 3B, F ), basal dorsolateral sclerites of the endosoma short, round, and smooth or subtly striated longitudinally ( Fig. 3B )....... A. maya Dispons, 1971

3 Quadrate cell of corium of hemelytra weakly delineated and is not completely outlined by light coloration ( Fig. 1C ), medial process of pygophore of males V-shaped with narrowly separated rami ( Fig. 2C ), basal dorsolateral sclerites of the endosoma relatively narrow and short, constricted at middle ( Fig. 3C ), dorsal endosomal surface with about 26 peg-like denticles (proximal denticles forming two orderly rows) ( Fig. 3C )......................................... A. pipil Dispons, 1971

- Quadrate cell of corium of hemelytra outlined entirely (or strongly delineated on at least three sides) by light coloration ( Fig. 1D ), medial process of pygophore of males lyre-shaped with widely separated rami ( Fig. 2E–F ), basal dorsolateral sclerites of the endosoma relatively broad throughout, not constricted at middle, dorsal endosomal surface with about 40 peg-like denticles (proximal denticles clustered) ( Fig. 3D ).................................................. A. venosus Stål, 1872

Figures

FIGURE 1. Dorsal habitus images of (A) A. immundus Bergroth, 1898 [♂ LECTOTYPE = UCR_ENT 00040816], (B) Apiomerus maya Dispons, 1971 [♀ = UCR_ENT 00013169, ♂ HOLOTYPE = UCR_ENT 00038047], (C) A. pipil Dispons, 1971 [♀ = AMNH_PBI 00218895, ♂ = UCR_ENT 00032865], and (D) A. venosus Stål, 1872 [♀ = UCR_ENT 00031790, ♂ = UCR_ENT 00032336]. All scale bars represent 4 mm.

FIGURE 2. (A–F) Caudal views of the pygophores (pyg) of males of the maya species group displaying the bifid medial process with rami (rm). In these taxa, the base of the medial process is greatly reduced giving the impression of the rami being inserted directly on the posterior rim of the pygophore. The rami are often broadly spaced from one another and render the medial process either V-shaped, as frequently observed in A. pipil (see C), or lyre-shaped (most male A. venosus). Figs. A– F are not to scale. (G–J) Dissected right parameres. All scale bars for Figs. G– J represent 0.25 mm.

FIGURE 3. Dorsal (A–D) and lateral (E–H) views of the aedeagus of males of the maya species group.An arrow-shaped dorsal phallothecal sclerite (dps) is commonly seen in males of these species (subconical in A. immundus). Note the paired triangular projections (tp) positioned basally on the dps of Apiomerus maya (B & F); these projections are absent in other maya group taxa. The basal dorsolateral sclerites of the endosoma (bdls) can be short and round (A. maya), moderately elongated with fine sculpturing basally (A. immundus), or greatly elongated and slightly twisted (A. pipil and A. venosus). The number of peg-like endosomal denticles (ed) aligned longitudinally along the distal dorsal lobes of the endosoma (ddl) varies across the group. In some taxa, notably A. immundus and some A. venosus, lateral sclerotizations of the endosoma (ls) may be observed along the endosoma’s proximal dorsolateral surface. All scale bars represent 0.5 mm.

FIGURE 4. Examples of intraspecific polychromatism across ranges of maya species group taxa.

FIGURE 5. Apiomerus venosus lectotype dorsal habitus (A), specimen labels (B), and caudal view of pygophore (C). The “Allotypus” label associated with this specimen is a curatorial artifact. Dorsal habitus (D) and labels (E) of the A. tristis lectotype (UCR_ENT 00048736). Figures A and D are not to scale. A–C photographed by Gunvi Lindberg (© 2022 NHRS). Original photos cropped, light levels and contrast adjusted. Made available by the Swedish Museum of Natural History under Creative Commons Attribution 4.0 International Public License, CC-BY 4.0.