Aoplonema Knight

Forero, D., 2008, Revision And Phylogenetic Analysis Of The Hadronema Group (Miridae: Orthotylinae: Orthotylini), With Descriptions Of New Genera And New Species, And Comments On The Neotropical Genus Tupimiris, Bulletin of the American Museum of Natural History 2008 (312), pp. 1-172 : 16-25

Aoplonema Knight

Type species: Hadronema princeps Uhler, 1894 (by original designation).

Hadronema (Aoplonema) Knight, 1928: 177 [n. subgen.]; Carvalho, 1958: 68 [catalog]; Henry and Wheeler, 1988: 410 [catalog].

Aoplonema: Kerzhner and Schuh, 1995: 4 [revised status]; Schuh, 1995: 81 [catalog].

DIAGNOSIS: Recognized by the overall reddish coloration (fig. 1), the narrow, almost delicate body (fig. 1), the vestiture composed of simple decumbent and sericeous setae (fig. 4D), the cylindrical phallotheca with a basal enlargement on the left side (figs. 6, 7), and the vesica with a single deeply cleft spicule forming two portions, with the left portion apically with two cephaladdirected rami (figs. 7, 10, 13).

Aoplonema is easily distinguished from other taxa of the Hadronema group by the particular type of vestiture, the presence of a single deeply cleft spicule of the vesica, and by the striking red and black overall coloration. It resembles Scutomiris in having two types of setae on the dorsum, simple structure of legs, convex frons, long dorsal opening of the phallotheca, and basal left protuberance on phallotheca; it is distinguished by the shorter and more decumbent simple setae on dorsum, the noninflated scutellum, and a single deeply cleft spicule of the vesica. Similar also to Aoplonemella in having a convex frons and simple structure of the legs, but easily distinguished by the vestiture with sericeous setae and by the vesica with one spicule with two portions, the left one with two rami.

REDESCRIPTION: Male: Usually delicate species, elongate, medium to large, total length 3.56–5.98. COLORATION: Red with dark areas and pale markings on hemelytra (fig. 1). HEAD: Reddish black. THORAX: Pronotum reddish black, sometimes almost orange. Hemelytra: Dark brown with pale costal margins, sometimes whitish cuneus with reddish markings. Legs: Red, reddish black, or dark brown. ABDOMEN: Reddish black. SURFACE AND VESTITURE: Surface smooth, dull, beset with dense macrotrichia; dorsum covered with simple short decumbent or semidecumbent setae, intermixed with sericeous setae (fig. 4D). STRUCTURE: HEAD (fig. 4A): Transverse, gently to strongly declivent, from oval to nearly oblong in lateral view; anteocular region short, less than one-third of head length, sometimes about one-third head length (fig. 5), beset with short simple setae; clypeus weakly protruding basally, barely visible in dorsal view, with one medial and two lateral longitudinal areas of irregular shiny spots; frons rounded to nearly flat, with two longitudinal ovate areas of irregular small shiny spots; vertex nearly flat, weakly excavated, with paired dark dull areas next to eyes; transverse carina elevated, not impressed, with a row of suberect simple setae; mandibular and maxillary plates subquadrangular, occupying about half the height of head, apices rounded; buccula not expanded laterally, beset with short or mediumsized simple setae; gena with scattered medium-sized simple setae below eye, vertical longitudinal patch of simple setae adjacent to base of maxillary plate; gula small, shorter than length of buccula, sometimes about as long as buccula; eyes oval in lateral view, rounded in dorsal view, from large to medium-sized, usually surpassing dorsal margin of head in lateral view, sometimes barely reaching dorsal margin, in dorsal view adjacent to anterior margin of pronotum; labrum narrow, acute, shorter than buccula; labium barely surpassing mesocoxa, beset with short setae, segment I dull, II–IV shiny; antennal segment I barely greater in diameter than II, II and III of subequal diameter, IV with the smallest diameter, segment I less than one-third of II, II and III subequal in length, IV the shortest. THORAX: Collar narrow, flat; pronotum trapezoidal, lateral margins weakly marginate, anterior and posterior margins straight, anterior angles rounded, posterior angles broadly rounded, surface nearly flat, inclined, posterior lobe transversely rugose; calli distinct, from nearly flat to weakly elevated, with scattered irregular shiny spots; mesoscutum usually not exposed, covered by posterior margin of pronotum, except most lateral portions; scutellum triangular, nearly equilateral, apex weakly acute, disc mostly flat, weakly round- ed along lateral margins; pleural area with a few short simple setae; metathoracic spiracle margin with conspicuous evaporatory area; metepisternum beset with dense macrotrichia, evaporatory area normal, dorsal margin inclined, nearly reaching dorsal portion of metacoxa, peritreme ovoid and beset with short and dense microtrichia (fig. 4B); prosternum with a patch of dense, short, simple setae (fig. 4A). Hemelytra: Nearly parallel, sometimes weakly curved before costal fracture; clavus flat, elevated with respect to corium and deflexed along claval suture; corium deflexed laterally along medial fracture; cuneus nearly flat, sometimes weakly deflexed, barely longer than wide (ratio about 2.6) or much longer than wide (ratio at least 3); membrane about half as long as hemelytron. Legs: Coxae elongate, with sparse short simple setae, more densely set on anteroventral surface; trochanters ovoid, with dense short simple setae; femora nearly cylindrical, gently narrowing distally; pro- and mesofemur of subequal width and length, metafemur barely greater in diameter, about 1.4 times longer than pro- and mesofemur, femora covered with short sparse setae; tibiae nearly cylindrical, of subequal width, weakly expanded apically on pro- and mesotibia, longer than femur and trochanter combined, surface covered with short sparse setae and a few scattered spiniform setae; tarsus about 2.6 times shorter than femur, cylindrical, barely lesser in diameter than tibia, first tarsomere the shortest, second tarsomere weakly shorter than third, third the longest, first tarsomere ventrally covered with short dense setae; pretarsus as in figure 4C. ABDO- MEN: Sternites with medium-sized dense simple setae. GENITALIA: Genital capsule subtriangular (fig. 6); aperture reclined, nearly ovoid, about half the length of genital capsule, weakly turned left, anterior margin not well sclerotized (fig. 6); ventrolateral right projection very small, blunt, almost nonexistent; proctiger reaching and surpassing caudal end of genital capsule (fig. 6); cuplike sclerite surpassing or barely reaching apex of genital capsule, right portion more elevated and projecting more caudad than left one, bases barely projecting cephalad beyond supragenital bridge; proctiger surpassing apex of genital capsule (fig. 4F); supragenital bridge weakly sclerotized but clearly visible under compound microscope, located above insertions of parameres; insertion of right paramere barely above left (figs. 4E, 6); left paramere sickle-shaped, apicoventral process acute (fig. 6); right paramere hatchet-shaped in medial view, body elongate, apically flattened, nearly truncated at the apex, with a small proximal blunt prolongation, medial caudal surface with numerous small tubercles, flat acute tubercle on dorsal angle directed medially, inner surface finely tuberculate (fig. 6); phallotheca nearly cylindrical, uniformly sclerotized, parallel-sided, basal lateral left side enlarged (figs. 6, 7), opening dorsal, longitudinal, of parallel margins, nearly reaching phallobase (fig. 7); vesica with a single spicule, deeply cleft forming two portions, basally expanded (figs. 7, 10, 13); left portion usually flattened dorsoventrally, rounded and denticulate at the apex, sometimes compressed laterally and less denticulate, distally with two prolongations (rami), apical and preapical, projecting dorsocephalad (figs. 7, 10, 13); rami usually weakly sinuate and directed to the right, long or short (figs. 7, 10, 13), apex weakly expanded, heavily denticulate; right portion about half as long as left one, inserted approximately at basal third of spicule, narrowing toward apex, strongly curved upward, vary rarely sinuate, apex denticulate or not, sometimes weakly expanded, in dorsal view strongly turned medially or weakly laterally, sclerotized part of ductus seminis long, located at base of spicule, about as long as right portion of spicule (figs. 7, 10, 13).

Female: Similar to male but usually larger, more ovoid, total length 3.84–5.15. COLOR- ATION: Similar to male (fig. 1). ABDOMEN: Sternite IX usually dark red, sometimes red or bright red (fig. 1A–C, arrows). SUR- FACE AND VESTITURE: As in male. STRUCTURE: Mostly similar to male. HEAD: Always oval in lateral view, anteocular region about half as long as head length; eyes barely smaller, never reaching dorsal margin of head. GENITALIA: Subgenital plate triangular, elongate, much longer than wide, very acute on apex, barely projecting beyond middle of sternite VIII (fig. 9); base of ovipositor located nearly at longitudinal midpoint of abdomen; interramal sclerites well sclerotized, with irregular margins, subrectangular (fig. 8); dorsal lobe of interramal sclerite as an inverted triangle in dorsal view, medial margin subapically enlarged, truncate area before round apex, with scat- tered microtrichia, strongly denticulate apically; dorsal margin of posterior wall not covered with microtrichia; sigmoid process projecting cephalad, strongly emarginate in anterior view, weakly denticulate (fig. 8); medial process neither distinct nor sclerotized; dorsal labiate plate without any sclerotized medial areas; sclerotized rings oblong, usually subrectangular, posterior margin usually produced as an acute process, lateral margin recurved, medial and lateral margins thick, weakly curved, usually produced anteriorly and turned medially, accessory sclerite usually enlarged, weakly rounded, and broadly denticulate, or small and acute at apex (fig. 8); internal surface of dorsal labiate plate between anterior lateral margins covered with strong microtrichia; ventral labiate plate on ventrocaudal margin not conspicuously produced; anterior wall simple and membranous, inner margin of first gonapophyses symmetrical (fig. 9).

DISTRIBUTION: Widely distributed from the 100th meridian to the west, and from Canada to Baja California in Mexico (fig. 14).

HOST ASSOCIATIONS: Although there is some information regarding host-plant associations, no large series of host-associated specimens is available to draw conclusions. In some instances it seems that there is at least some preference for Lupinus (Fabaceae) and Salvia (Lamiaceae) , but usually what is found is a mix of several unrelated groups of plants. As in Hadronema , species of Aoplonema have been associated either with meloid beetles or with cantharidin traps ( Pinto, 1978; Young, 1984a, 1984b).

DISCUSSION: Species of Aoplonema are rather variable in coloration (fig. 1) and male genitalia, in particular regarding the vesica structure (figs. 7, 10, 13). Despite this variation, head and hemelytral structure and minor differences in coloration patterns allow for species separation.

The following proposal of species delimitation is presented as the best hypothesis to be deduced from the available data. Future work, including molecular markers, may show that the variation exhibited for instance by A. princeps is indeed a complex of morphologically difficult-to-separate species.

Complex male genitalic structures, in particular the vesica, are helpful in delimiting species within Orthotylini (e.g., Schuh, 1974; Stonedahl and Schwartz, 1986; Wyniger and Burckhardt, 2003). The vesica in Aoplonema , however, may vary greatly even within populations, as exemplified by specimens collected in the same locality at the same time (e.g., fig. 7: AMNH_PBI 00102790, AMNH_PBI 00102791), and thus it is of little value in discriminating species based on absolute differences. Nonetheless, overall differences, such as length of rami, are useful to assess species limits. Variability usually is not clearly stated in species’ descriptions and it is rarely documented in Orthotylini (but see Pagola-Carte, 2006: fig. 4; Pagola-Carte and Zabalegui, 2006: fig. 3). I have documented the vesical structure in Aoplonema because it is highly variable (see figs. 7, 10, 13).

The supragenital bridge in the genital capsule is usually broad and well sclerotized in Hadronema group taxa. Nevertheless, in Aoplonema it is narrow and not well sclerotized, making it difficult to observe under the dissection microscope, although it is clearly visible under the compound microscope.

The structure of the dorsal lobe of the interramal sclerite usually is constant among species (e.g., Hadronema ; see also Slater, 1950), and it may help to distinguish species. Nevertheless, Aoplonema species show a certain degree of variability (see also Pagola-Carte, 2006; Pagola-Carte and Zabalegui, 2006), apparently related with vesica variability, which prevents using these structures as characters for distinguishing species.

Because of the variability of male and female genitalic structures, other characters were explored to assess species discrimination. Head and hemelytra structures are useful in this task. In one group of specimens, which includes the new species A. nigrum and A. rubrum , the males have the anteocular part of the head less than one-third of its length, large eyes surpassing the dorsal margin, and long hemelytra and cuneus. The remaining group, which includes A. princeps only, has a longer anteocular region and shorter hemelytra. The various color morphs of the latter have been described as A. princeps , A. uhleri , and A. uniforme .

Aoplonema princeps was described as having a whitish cuneus and reddish body (fig. 1A) ( Uhler, 1894); A. uhleri was de- scribed as ‘‘bright red’’, including the femora, pronotum, and pleura (fig. 1D) ( Van Duzee, 1928); and A. uniforme was described as having a ‘‘uniformly black cuneus’’ and ‘‘orange yellow’’ femora (fig. 1F) ( Knight, 1928). Based on the original color descriptions of A. princeps , A. uhleri , and A. uniforme , and the examination of type material, specimens were sorted into these three categories, plus an additional apparently distinct population from Colorado (fig. 1B), whose specimens are darker than the others and the females have a bright red ninth sternite (fig. 1B, arrow). Nevertheless, several difficult-to-place specimens due to intermediate coloration prevented unambiguous placement for many of them (see examples under A. princeps discussion), and therefore sorting was considered preliminary.

Because male genitalic structure and dorsal coloration patterns were shown to be variable within the three nominal species under consideration, PCA and CVA analyses were performed to further assess their limits using standard measurements (see table 1). These analyses were also taken into consideration because the Colorado specimens were larger than specimens from other areas, and thus it was possible that some size-related character may be helpful to distinguish among species.

For PCA and CVA analyses, males of typical coloration for each nominal species representing the geographic range were measured: A. uhleri (n 5 15), A. princeps (n 5 31), A. uniforme (n 5 13), the Colorado population (n 5 30), A. nigrum (n 5 12), and A. rubrum (n 5 12). PCA is particularly useful to summarize in a few vectors the variability observed ( Pimentel, 1992), and it is helpful when populations need to be identified in mixed samples (Claridge and Gillham, 1992). PCA was carried out for clustering examination among Aoplonema species , excluding A. nigrum and A. rubrum , which are clearly longer and have a different head structure. The PCA was based on a variance-covariance matrix since all variables are morphometric measures and complete independence is not assumed. The goal of the CVA was to find the best possible separation among groups of Aoplonema by maximizing variation among groups and minimizing intraspecific variation ( Pimentel, 1992). Aoplo-

TABLE 2 PCA Values for Aoplonema, Exclusive of A. nigrum

and A. rubrum

Coefficients for the first two components represent the relative contribution of the variables to each component.

nema nigrum and A. rubrum were included in this analysis for comparison purposes. Data were analyzed using the computer software PAST ver. 1.61 ( Hammer et al., 2001).

The first two axes (PC1 and PC2) of the PCA of Aoplonema measurements account for 91% of the variation (fig. 11). PC1 explains most of the variation (85%), which represents the overall length variation among individuals (table 2). PC2 contrasts mainly the width of pronotum and scutellum with antennae measurements. The rest of the components can be thought of as representing residual variance in underlying variables that might be related to age, environmental, host-plant, or geographical variation (Claridge and Gillham, 1992). Figure 11 shows the high degree of variation of the four groups without discontinuity in the two principal components. Aoplonema princeps is highly variable in both components, including most of the variation exhibited by A. uniforme , and about half that of A. uhleri . Aoplonema uniforme tends to be as narrow as A. princeps , whereas A. uhleri is apparently slightly wider, which is reflected in the analysis. The Colorado population is larger than both A. princeps and A. uniforme , but it is intermediate with A. uhleri . This nearly continuous variation suggests that there is not a satisfactory way of separating the selected groups.

Using CVA to discriminate among groups within the complex of A. princeps , A. uhleri , A. uniforme , and the Colorado population (fig. 12) demonstrates that no adequate separation is achieved with the measurements used, and large overlapping areas occur among the groups. The Colorado population had less overlap with the other taxa, but no morphological characters were found to distinguish these specimens from other taxa in Aoplonema . Unambiguous separation was achieved among A. nigrum , A. rubrum , and the rest of the Aoplonema specimens, even when males of both A. nigrum and A. rubrum are similar in size (i.e., measurements). The latter is congruent with structure of the anteocular region, which was not measured for the analyses. As supported by the classification coefficient based on the extract- ed canonical variates, A. princeps , A. uhleri , A. uniforme , and the Colorado population are morphologically inseparable, at least based on the variables used in these analyses.

The high variability found among groups may be related with environmental effects along the geographic distribution. Host plants may influence different phenotypic traits on associated insects, including size ( Agrawal, 2001; Carrol and Boyd, 1992; Kirk, 1991; Mopper, 1996; Peppe and Lomônaco, 2003). Nutritional quality of host plants is probably the most important factor to influence insect size (e.g., Amarillo-Suárez and Fox, 2006; Clissold et al., 2006). Because the host-plant range is quite diverse for these taxa (appendix 2), it is plausible that coloration and size differences are due to plant effects.

Because no diagnostic character, or combinations of characters, was found to unambiguously separate A. uhleri , A. uniforme , and A. princeps , I propose that they are synonyms. Aoplonema princeps , based on priority, is the senior name.