Laemosaccus texanus Champion, 1903

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 : 934

Laemosaccus texanus Champion, 1903

( Figs. 19 , 30 )

Laemosaccus texanus Champion 1903: 285 .

Redescription. Male. Length 3.4 mm, width 1.6 mm ( Fig. 19 ). Robust, subcylindrical in cross section, broadly rounded behind, more abruptly and narrowly so in front, black throughout; head, pronotum, and elytra glabrous; metasternum and abdomen ventrally with punctures each with a small, inconspicuous, silvery seta, setae more slender on basal half of femora and basal margin of tergite 7. Head hemispherical, 0.8 mm wide, rostrum rounded-terete, longitudinally rugose, medially carinate for middle third between weaker carinae on basal half, medial carina ending within V-shaped groove on apical half, groove ending at rostral apex, 0.6 mm long, antennae inserted at middle. Pronotum gibbous, almost box-like, convex at base, strongly, abruptly constricted before anterior margin, broadest just before middle with lateral margins very shallowly arcuate, 1.3 mm long, 1.45 mm wide, convex in lateral view, coarsely, evenly punctate, punctures rounded and separate on basal half, becoming longitudinally confluent and parallel on anterior half, with very distinct, fine, medial carina for entire length. Elytra subequal to pronotum at base, narrowing then broadening again behind humeri, 2.1 mm long, 1.6 mm maximum width, elytral striae much narrower than intervals, striae coarsely punctate, intervals transversely ridged and producing weakly toothed effect in lateral view. First abdominal ventrite very slightly concave and emarginate at midline at posterior margin, with setae less conspicuous. Profemora with broad, truncate, backward-projecting ventral tooth beyond middle and strong dorsal carina extending nearly to apex; mesofemora with small, acute, forward-projecting ventral tooth before middle, metafemora unarmed. Genitalia as in Fig. 30 ; aedeagus 0.60 mm long.

Female. As male, but rostrum proportionately somewhat longer.

Specimens Examined. USA: Texas: Cameron Co., Sabal Palm Grove, Audubon Preserve , 1- 2.09.1978, J. E. Wappes ( JEWC) , 25- 26.10.1980, Downie & Wappes ( FMNH) , 13.10.1987, N. M. Downie ( FMNH) ; Brownsville, Sable (sic.) Palm Grove , 10.08.1983, M. Kaua \lbars ( CMNC) ; Brownsville, Wickham (holotype ♂, BMNH) , 24.06.1969, Board & Hafernik ( TAMU) ; Palmito Battle Field , 26.05.1971, Burke, Broad & Clark ( TAMU) , San Tomas, Brownsville , 07.1929, C. Schaeffer ( BYU) , Esperanza Rch., Brownsville , 18, 22, 23, 26.08.[year?] C. Schaeffer ( BYU) ; Hidalgo Co., LRGVNWR [Lower Rio Grande Valley National Wildlife Refuge], Loma Unit, Massey Way ( Rd. ), 25.96012°N, 97.25343°W, 5- 6.06.2009, E. Riley-1031 (TAMU-ENTO X0833809) ; Travis Co. Camp Mabry Nat. Guard, Austin, N 30.321 W97.767, 8- 25.04.2005, J. C. Abbot, Malaise-C ( TAMU) ; [Uvalde Co.], Uvalde , 23.05.1935, J. N. Knull ( OSU) . Mexico: San Luis Potos´ı : 10 mi. E Xilitla, 300 ft, 25.07.1954, Univ. Kans. Mex. Expedition ( SEMC) ; Tamaulipas: 20 mi. SW Tampico , 25.03.1951, W. P. Stephen ( SEMC) ; Veracruz: Cordoba, Dr. A. Fenyes ( CASC) . Costa Rica: Guanacaste: OTS Palo Verde Sta. , 29 km WSW Ca ~ nas, 10°21’ N 85°21’ W, 9, 10, 13.07.1976, H. A. Hespenheide, Malvaceae (3. CHAH) .

Hosts. Horace Burke directed me to the following quotation from Townsend (1903): “Two specimens…were taken on stalks of Abutilon holosericeum at Santo Tomas, June 6 th. On June 18 th, two specimens were found in cells inside dead stalks of the same plant, and one on the stems of a live plant. The species breeds in the stalks. A specimen was taken by Wickham on a live cotton stalk, June 28 th …” The Wickham specimen may be the one Champion made the type of L. texanus .

Discussion. Laemosaccus texanus and the following species, as well as at least one undescribed species from Panama in my collection and perhaps more than one additional species from Mexico, share the following characters: black coloration; profemora with dorsal carina and truncate, basally projecting tooth; and hosts in the Malvaceae . The series of three specimens from Costa Rica are tentatively included as this species; they share the tricarinate rostrum, similar male genitalia, and an herbaceous malvaceous adult host, although the rostrum of the female is proportionately somewhat longer. Among specimens from Texas, males vary in size from 2.45 to 3.30 mm (mean = 3.04 mm, n = 6); females vary from 2.60 to 3.60 mm (mean = 3.20 mm, n = 11). This species is figured in Bug- Guide (bugguide.net/node/view/915682/bgimage), as well as the tricarinate rostrum of the male bugguide.net/node/view/915686/bgimage.

Figures

Figs. 19–24. Laemosaccus species, dorsal and lateral views of aedeagus and paramere. 19) L. andersoni; 20) L. arizonensis; 21) L. bimaculatus; 22) L. burkei; 23) L. clytrinoides; 24) L. howdenae.

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.