Laemosaccus, SCHÖNHERR, 1826

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 : 936-937

KEY TO ADULTS OF THE SPECIES OF LAEMOSACCUS OF BAJA CALIFORNIA AND AMERICA NORTH OF MEXICO

1. Species entirely black and from Texas or Arizona; profemora carinate on dorsal side. Hosts: Malvaceae . L. texanus group ........ 2

1 ʹ. Species black with larger or smaller red posthumeral spot on elytron, or if entirely black, then from Baja California Sur; profemora not carinate on dorsal side. Hosts: Fagaceae , Fabaceae , Malvaceae . L. nephele group .............................................. 3

2. Texas; rostrum dorsally strongly 5-carinate, punctures on pronotum confluent and parallel to midline. Host: Abutilon ............... .......................................... L. texanus

2 ʹ. Arizona; rostrum dorsally weakly 3-carinate; punctures on pronotum confluent and convergent on midline. Host: Gossypium ....... .......................................... L. gossypii

3. Abdominal tergites 7 and 8 visible; males .... 4

3 ʹ. Only abdominal tergite 7 visible; females ........................................ 18

4. Red spots on elytra small, usually <0.25X elytral length, or absent; Baja California ............... 5

4 ʹ. Red spots on elytra usually>0.5X elytral length; Massachusetts, Ontario, and Colorado south to Florida, Arizona, and mainland Mexico............................................ 6

5. Basal half of rostrum shiny, sparsely punctate, separate lines of dense white setae from antennal insertions to top of eyes; aedeagus strongly arcuate in lateral view; widely distributed on the Baja California Peninsula ..... ............................................. L. westcotti

5 ʹ. Basal half of rostrum matte, densely punctate, setae at sides of rostrum from antennal insertions to middle of eyes; aedeagus moderately curved only at base, otherwise straight; restricted to southern end of Baja California Sur ................. L. peninsularis

6. Frons with dense, white setae, obscuring area between eyes and on rostrum only above antennal insertions; Hosts: Fabaceae ; Southwestern USA.................. L. burkei

6 ʹ. Frons glabrous, or if with white setae, not obscuring area between eyes and on rostrum only on sides or sparsely below antennal insertions. Hosts: Quercus .................... 7

7. Abdominal tergite 8 conspicuously domed in lateral view; Arizona ........... L. andersoni

7 ʹ. Abdominal tergite 8 more or less convex in lateral view, but not domed .................. 8

8. Eastern species – Oklahoma, central Texas, and eastward ..................................... 9

8 ʹ. Southwestern species – western Texas, New Mexico, Arizona, and Colorado ........... 10

9. Orange elytral spot large, reaching anterior and lateral margins of elytra; pronotal sculpture of rather large, distinct punctures not confluent on anterior half .................. .......................................... L. nephele

9 ʹ. Orange elytral spot smaller, usually not reaching anterior and lateral margins of elytra; pronotal sculpture of small, fine punctures becoming confluent and parallel to midline on anterior half ........... L. obrieni

10. Larger species (>3.0 mm); rostrum with at least white setae on sides above antennal insertions ........................................ 11

10 ʹ. Smaller species (<3.0 mm); rostrum glabrous, or if with setae on sides, with tufts of setae on 1 st abdominal ventrite ............ 14

11. Anterior surface of rostrum and propygidium uniformly, conspicuously setose; elytra uniformly setose; Arizona ............. L. howdenae

11 ʹ. Anterior surface of rostrum, elytra, and abdominal tergite 7 glabrous .................. 12

12. Species usually> 4 mm; with conspicuous, strong teeth on elytral intervals 3 at middle and 5 beyond middle; rostrum 1.5X as long as depth of eyes; aedeagus tapering, acute, with black central region ................. L. vaurieae

12 ʹ. Species usually <4 mm; only slightly toothed on elytral intervals 3 and 5; rostrum short, subequal to depth of eyes; aedeagus variable ........... 13

13. Aedeagus uniformly pale brown with sides subparallel, apically broadly rounded ........ .................................... L. bimaculatus

13 ʹ. Aedeagus with black central region, sides convergent, apically narrowly rounded ...... ........................................... L. obrieni

14. Metasternum with medial glabrous area; 1 st abdominal ventrite with dense medial tufts of erect, hair-like setae; Arizona .................. ..................................... L. arizonensis

14 ʹ. Medial areas of metasternum and 1 st abdominal ventrite essentially unmodified ............... 15

15. Aedeagus uniformly very pale brown, apex acuminate; tooth on profemur small, acute; Arizona .......................................... 16

15 ʹ. Aedeagus brown with black internal structures near apex, apex narrowly rounded or truncate; tooth on profemur strong.. .... 17

16. Rostrum broadened toward apex, with medial impunctate area; ventral surface densely setose; orange posthumeral spot almost reaching anterior margin of elytra; abdominal tergite 7 with dense, long, erect or semierect, hair-like setae .......... L. clytrinoides

16 ʹ. Rostrum not broadened toward apex, matte; ventral surface sparsely setose; orange posthumeral spot far from anterior margin of elytra; abdominal tergite 7 with sparse, appressed or semi-erect, hair-like setae ........ .................................... L. browerorum

17. Aedeagus strongly curved, uniformly slender in lateral view, apex truncate; small spot of white setae on elytral suture behind scutellum ..................................... L. rileyi

17 ʹ. Aedeagus weakly curved at base and variable in thickness in lateral view, apex narrowly rounded; elytral suture glabrous behind scutellum .............................. L. obrieni

18. Rostrum terete, more or less coarsely punctate or sculptured ....................... 19

18 ʹ. Rostrum more or less cylindrical, short, straight, inconspicuously punctate and shiny in frontal view ................................. 23

19. Abdominal tergite 7 strongly domed in lateral view; Arizona .............. L. andersoni

19 ʹ. Abdominal tergite 7 more or less convex, but not domed ....................................... 20

20. Abdominal tergite 7 glabrous; small species usually <3.5 mm long ....................... 21

20 ʹ. Abdominal tergite 7 conspicuously setose; large species usually>4.0 mm long; rostrum setose, without medial polished area.. .... 22

21. Red posthumeral spot>0.5X elytral length; New Mexico and Arizona south to Chihuahua, Durango, and Sonora ........... L. clytrinoides

21 ʹ. Red posthumeral spot absent or <0.5X elytral length; Baja California Sur ..................... .................................... L. peninsularis

22. Anterior surface of rostrum and abdominal tergite 7 uniformly, conspicuously setose.. ....................................... L. howdenae

22 ʹ. Anterior surface of rostrum glabrous, abdominal tergite 7 glabrous at middle, with tuft of semi-erect setae at apex ............ L. vaurieae

23. Frons with conspicuous white setae along inner margins of eyes and extending onto sides of rostrum above antennal insertions ............. 24

23 ʹ. Frons glabrous or with a few setae on sides of rostrum at base ................................ 25

24. Red spots on elytra small, usually <0.25 length of elytra; Baja California .............. ......................................... L. westcotti

24 ʹ. Red spots on elytra usually>0.5 length of elytra; Texas or Arizona ........... L. burkei

25. Rostrum continuous with profile of frons and eyes, or only slightly angled forward ........ 26

25 ʹ. Rostrum conspicuously angled forward from profile of frons and eyes; small species, usually <3.5 mm long ....................... 27

26. Species usually <3.5 mm; orange spots on elytra large, often extending to anterior margin and contiguous at suture; eastern North America west to eastern Oklahoma and central Texas .................. L. nephele

26 ʹ. Species usually> 3.5 mm; orange spots on elytra often not extending to anterior margin or contiguous at suture; western Texas to Arizona ......................... L. bimaculatus

27. Elytral spots ≤0.5 elytral length, far from anterior margin; abdominal tergite 7 glabrous; western Texas ......................... 28

27 ʹ. Elytral spots>0.5 elytral length, reaching or close to anterior margin; abdominal tergite 7 with area of semi-erect, hair-like setae at apex; eastern USA to Arizona ............. 29

28. Abdominal ventrites densely covered with multifid setae; elytral striae with indistinct punctures; pronotum reticulate-punctate, punctures separate; western Texas ............ .............................................. L. rileyi

28 ʹ. Abdominal ventrites 3–5 sparsely covered with simple, hair-like setae; elytral striae with coarse punctures; pronotum reticulatepunctate, punctures confluent on anterior half; Arizona .................. L. browerorum

29. Metasternum and 1 st abdominal ventrite broadly glabrous at middle; rostrum sparsely, minutely punctate; southern Arizona ........ ..................................... L. arizonensis

29 ʹ. Metasternum and 1 st abdominal ventrite uniformly densely setose; rostrum more densely, distinctly punctate; eastern USA to Arizona. .. ... .. .. .. .. .. .. .. .. ... L. obrieni