Laemosaccus browerorum Hespenheide, 2019

Hespenheide, Henry A., 2019, A Review of the Genus Laemosaccus Schönherr, 1826 (Coleoptera: Curculionidae: Mesoptiliinae) from Baja California and America North of Mexico: Diversity and Mimicry, The Coleopterists Bulletin (MIMICRY AND LAEMOSACCUS In an earlier paper (Hespenheide 1996), I presented the hypothesis that species of Laemosaccus of the L. nephele group with red humeral spots on the elytra were Batesian mimics of members of the Chrysomelidae in the subfamily Clytrinae. There is no evidence that Laemosaccus species are distasteful, and what is either L. nephele and / or L. obrieni have been reported as prey items of birds (Beal 1912). In Cave Creek Canyon, Cochise County, Arizona, 21 forms (species and “ subspecies ”) of Clytrinae were hypothesized to be the primary models of 22 species of mimics in the families Anthribidae (one species), Bruchidae (two species), Buprestidae (four species), Chrysomelidae, subfamily Cryptocephalinae (three species), Coccinellidae (six species), Curculionidae, subfamily Baridinae (one species), and Laemosaccus (five species). Of these, the coccinellids and the cryptocephaline chrysomelids are probably distasteful Mullerian co-mimics. Ecologically, the species of Laemosaccus co-occurred with their clytrine models on both desert legumes and canyon oaks, although more clytrine species occurred in the desert and more Laemosaccus species occurred in the canyons. Species of clytrines showing the mimetic pattern are common throughout Mexico (Bellamy 2003, who renamed the Mexican buprestid genus Acherusia Laporte and Gory, 1837 as Mimicoclytrina Bellamy to reflect their resemblance to clytrines), but decline in numbers of species and in the proportion of the clytrine fauna through Central America to Panama (Hespenheide 1996, fig. 2). Laemosaccus seems to follow a similar pattern. Mimicry is more common in large faunas, especially in wet tropical areas (Hespenheide 1986, 1995); because the largest clytrine fauna is in Mexico, the clytrine mimicry complex is also larger there (Hespenheide 1996). This complex has more members than I first enumerated and deserves further study. The evolution of mimicry produces resemblances between unrelated species (Laemosaccus and other putative mimics, with clytrines and perhaps other Chrysomelidae and Coccinellidae as models; see Hespenheide 1976, 1996) and selects against the divergence of related species. In Batesian mimicry - hypothesized to be the form of relationship between Laemosaccus and clytrines - the selection for precision of mimicry is stronger on the mimic (Laemosaccus), so that resemblances among them should be closer, regardless of ancestry. Close morphological resemblances based on ecology rather than ancestry may be termed mimetic homoplasy (Hespenheide 2005) and can make recognition of species difficult (as in Laemosaccus) or complicate phylogenetic analyses. I have speculated (Hespenheide 1996) that the sympatric “ subspecies ” of the clytrine models (Moldenke 1970) may in fact be reproductively isolated sibling species. It will be interesting to see whether or not genomic studies show the closeness of relationships among Laemosaccus species that the morphology suggests) 73 (4), pp. 905-939 : 928-930

Laemosaccus browerorum Hespenheide , new species

Zoobank.org/ urn:lsid:zoobank.org:act:B133EFA0-EBF9-441D-972E-211719F01736 ( Fig. 25 )

Description: Holotype Male. Length 2.35 mm, width 1.10 mm. Very robust, subcylindrical in cross section, broadly rounded behind, narrowly so in front, black except each elytron with broadly oval, red posthumeral spot on elytral intervals 2–9, about 0.75 mm long and not close to base, appearing trapezoidal from above; head, pronotum, elytra, and propygidium glabrous, thorax and abdomen ventrally and metafemora with punctures each with a small, inconspicuous, silvery seta, setae less dense and more slender on legs, longer, hair-like, semierect and transversely oriented on tergite 8. Head hemispherical, 0.50 mm wide, rostrum roundedterete, punctate, matte, 0.35 mm long, antennae inserted at middle. Pronotum weakly convex in cross section at base, very strongly constricted before anterior margin, abruptly gibbous posteriorad, 0.90 mm long, 1.00 mm wide, broadest anterior to middle, with lateral margins very shallowly arcuate on basal half, more strongly so in front, and convex in lateral view, coarsely, evenly punctate, punctures rounded and separate at base, becoming reticulate and somewhat confluent longitudinally on apical half, indistinct medial carina on basal half. Elytra wider than pronotum at base, sides nearly parallel, 1.45 mm long, 1.10 mm maximum width, elytral striae subequal in width to intervals, striae very coarsely rounded-punctate, intervals rounded, interval 3 very weakly toothed on middle third, interval 5 weakly toothed on apical half. Profemora with acute ventral tooth at middle, mesofemora with small ventral tooth, abdominal ventrite 5 0.5–1.0X length of ventrite 4 at middle. Genitalia as in Fig. 25 ; aedeagus 0.60 mm long.

Allotype Female. As male but rostrum subcylindrical, polished, very finely, inconspicuously punctate, glabrous, forming nearly 45° angle with plane of eyes, antennae inserted at basal third; tergite 7 convex, coarsely punctate, glabrous; 3.20 mm long, 1.60 mm wide.

Specimens Examined. Holotype: Arizona: Pima Co., Madera Cn, 7.1973, Dr. Lenczy ( USNM) . Allotype: Arizona: Santa Cruz Co., Santa Rita Mts., Madera Canyon , 9.08.2001, J. & A. Rifkind, C. Bellamy, oak / juniper zone ( WFBM) .

Etymology. This species is named in honor of the late Lincoln Brower and Jane Van Zandt Brower, whose studies on the effectiveness of Müllerian mimicry in monarch butterflies are classics.

Discussion. Laemosaccus browerorum is known only from the types from extreme southern Arizona. Ventrally, it is the least conspicuously setose of all species treated here. This small species is superficially similar to the following species in having the relatively small, red posthumeral spot placed farther posteriorly from the anterior margin of the elytra, but is distinctive in having a very strong pronotal collar, large punctures in the elytral striae, and an aedeagus in the males similar to that of L. clytrinoides , but even more acuminate.

Figures

Figs. 25–30. Laemosaccus species. Dorsal and lateral views of aedeagus and paramere: 25) L. browerorum; 26) L. rileyi; 27) L. vaurieae; 28) L. westcotti; 29) L. peninsularis; 30) L. texanus, dorsal and lateral views of aedeagus only. 31) L. peninsularis, dorsal habitus.