Laemosaccus peninsularis 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 : 933-934

Laemosaccus peninsularis Hespenheide , new species

Zoobank.org/ urn:lsid:zoobank.org:act:47106C54-07A3-4C54-8CCF-7B61090EE0C ( Fig. 29 )

Description, Holotype Male. Length 3.00 mm, width 1.35 mm. Very robust, subcylindrical in cross section, broadly rounded behind, more narrowly so in front, black except each elytron with small, rectangular, red posthumeral spot on elytral intervals 4–6, about 0.50 mm long; pronotum and elytra glabrous, thorax and abdomen ventrally and metafemora with punctures each with a silvery seta, setae nearly obscuring surface on metasternum, metepimera, and abdominal ventrite 1, sparser on proepimera and abdominal ventrites 2–5, head with setae on rostrum between base of eyes and antennal insertions, setae less dense and more slender on legs, hair-like, long, and transversely semi-erect on tergite 8. Head hemispherical, 0.80 mm wide, rostrum terete, matte, punctate, 0.45 mm long with faint median carina, antennae inserted at middle. Pronotum gibbous, convex in cross section, slightly constricted at base before anterior margin, 0.95 mm long, 1.25 mm wide, broadest at middle, lateral margins very weakly arcuate, more so in front than behind, slightly convex in lateral view, coarsely, evenly reticulate-punctate, with indistinct medial carina on basal half. Elytra slightly wider than pronotum at base, sides nearly parallel, 1.90 mm long, 1.35 mm maximum width, elytral striae narrower than intervals, striae indistinctly punctate, intervals carinate, intervals 3 and 5 weakly toothed. Abdominal ventrite 1 weakly angulateemarginate at middle. Profemora with broad, abruptly acute ventral tooth beyond middle, meso- and metafemora each with single very small ventral tooth, metafemora oval in cross section, widest at apex. Abdominal ventrites 3–5 subequal at middle, abdominal ventrites 1 and 2 each equal length of ventrites 3 + 4. Genitalia as in Fig. 29 ; aedeagus 0.70 mm long.

Allotype Female. As male but entirely black, rostrum 0.80 mm long, subcylindrical, polished, finely punctate, glabrous, forming 45° angle with plane of eyes, antennae inserted near base; frons with line of setae in front and behind eyes, broken above; tergite 7 convex, coarsely punctate, with patch of semi-erect, hair-like setae at ventral margin; 3.85 mm long, 1.75 mm wide.

Specimens Examined. Holotype: Mexico: Baja California Sur: Sierra La Laguna , 1770–1850 m, 30.08.1977, E. Fisher, R. Westcott ( CASC) . Allotype: Same data as holotype ( CASC) . Paratypes: Mexico: El Taste, Low, Cal., [coll of Chas Schaeffer] (3, BYU) ; Baja California Sur, same data as holotype (3, CASC) ; Ramal de los Naranjos , 28 km W Hwy 1, 28.08.1994, R. Morris (2, CMNC; 1, RFMC) ; 20–28 km W Ramal a los Naranjos , 28.08.1994, R. Turnbow (1, CMNC) .

Etymology. This species is named for the Baja California Peninsula, where it is apparently endemic.

Discussion. Laemosaccus peninsularis is restricted to Baja California Sur and its biology is unknown. It differs from L. westcotti by being less densely setose ventrally and glabrous on the front and having very different male genitalia. The female rostrum is proportionately about 1.5X longer than that of males. Males vary from 3.15 to 4.10 mm (mean = 3.55 mm, n = 5).; females vary from 3.15 to 4.10 mm (mean = 3.55 mm, n = 5).

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.