Acoma (Males), 1889

Warner, William B., 2011, Four new species of Acoma Casey, with a key to species in the genus (Coleoptera: Scarabaeidae: Melolonthinae), Insecta Mundi 2011 (172), pp. 1-17 : 6-9

Key to the Described Species of Acoma (Males)

1. Antennal club composed of 3 segments ..................................................................................... 12

— Antennal club composed of more than 3 segments; proximal segment of club may be short but at least 1/3 as long as other club segments .................................................................................. 2

2(1). Antennal club composed of 7 segments ( Fig. 16, 17 ) .................................. A. sexfoliata Saylor

— Antennal club composed of fewer than 7 segments ..................................................................... 3

3(2). Antennal club composed of 4 segments; elytral disc glabrous or setigerous ............................... 4

— Antennal club composed of more than 4 segments; elytral disc setigerous ................................ 8

4(3). Elytral disc glabrous .................................................................................................................... 5

— Elytral disc hairy ......................................................................................................................... 7

5(4). Sonora (Ciudad Obregon area), dark reddish brown ................................... A. gibsoni Howden

— Baja California peninsula; color various ..................................................................................... 6

6(5). Body color pale testaceous; NE Baja California area ................................... A. stathami Cazier

— Body color dark brown; W Cape area, Baja California Sur ............................ A. cazieri Saylor

7(4). Basal club lamella narrower and only about half as long as the other lamellae; vicinity of El Refugio, Baja California Sur ..................................................................... A. dilemma Saylor

— All club lamellae about same length and width ( Fig. 11 ); vicinity of Las Arrastras, Baja California (Norte) ................................................................................ A. quadrilaminata new species

8(3). Antennal club composed of 5 segments of equal length ( Fig. 22 ); body usually relatively elongate, narrow ....................................................................................................................................... 9

— Proximal antennal club lamella distinctly shorter and often narrower than other lamellae ( Fig. 14, 15 ); form robust ................................................................................................................ 11

9(8). Baja California peninsula .................................................................................. A. leechi Cazier

— Mainland Sonora species ............................................................................................................ 10

10(9). Color light (tan); clypeus emarginate apically; Desemboque area .............. A. mimica Howden

— Color dark reddish brown; clypeus semicircular to rounded-truncate; Hermosillo area ............... .................................................................................................................... A. evansi Howden

11(8). Clypeal suture tumid medially; anterior pronotal angles not or feebly produced; size small (5.5-6.5 mm) ................................................................................................................... A. rossi Saylor

— Clypeal suture flat medially; anterior pronotal angles usually strongly produced anteriorly ( Fig. 14, 15 ); size large (6.5-11.0 mm) ........................................................... A. robusta Van Dyke

12(1). Elytral disc with at least some short or long hairs ................................................................... 15

— Elytral disc glabrous; only marginal setae present ................................................................... 13

13(12). Antenna 10-segmented ( Fig. 9 ); clypeus often bidentate ( Fig. 1 , 8 ); dunes of the Gran Desierto in NE Sonora and NW Baja California, SE California and extreme SW Arizona .......................... .................................................................................................................. A. glabrata Cazier

— Antenna 9-segmented ( Fig. 7 , 26 ); clypeus truncate ( Fig. 6, 7 ) or rounded ( Fig. 26 ) ............... 14

14(13). Clypeus more or less pentagonal; color translucent, pale testaceous; metatibia with medial transverse carina relatively weak ( Fig. 6 ); Mohawk dune system east of Gila and Tinajas Altas Mountains , Arizona ................................................................. A. howdenorum new species

— Clypeal rounded, with lateral margins convexly arcuate ( Fig. 26 ) ; metatibia with medial carina strongly protruding, shelf-like ( Fig. 25 ); color dark reddish brown, elytra not translucent ( Fig. 24 ); Sonora, vicinity of Hermosillo ................................................ A. cimarron new species

15(12). Anterior tibia distinctly bidentate ( Fig. 4 ); head and pronotum appearing very smooth, anterior pronotal angles acute, drawn forward ( Fig. 2 ); Baja California Sur (vicinity of Mulege) .......... ......................................................................................................... A. westcotti new species

— Anterior tibia tridentate (e.g. Fig. 6 , 14-16 , 22, 23 , 26 ); head and pronotum distinctly sculptured, often strongly so (e.g. Fig. 1 , 10, 13 , 14-16 , 20-23 , 26 ); anterior pronotal angles various ..... 16

16(15). Anterior lateral margins of pronotum straight or arcuate; anterior pronotal angles usually obtuse or nearly so, not noticeably drawn forward near eyes (as in Fig. 1 , 6, 8 , 10 , 26 ) .................. 20

— Anterior lateral margins of pronotum slightly sinuate; anterior pronotal angles acute and slightly anteriorly extended near eyes (as in Fig. 2 , 14-16 , 22 ) .......................................................... 17

17(16). Clypeal margin apically rounded, truncate, or at most slightly emarginate (as in Fig. 2 , 6 , 21 ). ................................................................................................................................................ 18

— Clypeal margin usually distinctly emarginate medially, often bidentate (as in Fig. 1 ); Loreto to San Ignacio, Baja California ................................................................. A. confusa Van Dyke

18(17). Sonora, Mexico; sinuation of lateral pronotal margin before anterior angle generally obsolescent to obsolete; antennal club only slightly longer than funicle ................... A. martini Howden

— Baja California Sur; sinuation of pronotal margin usually more or less distinct; antennal club length various ......................................................................................................................... 19

19(18). Clypeus deeply cupuliform, free margin strongly reflexed; antennal club length only slightly longer than funicle; pronotum usually with discal setae; body length usually over 5 mm; Venancio to Santiago ............................................................................................ A. incognita Howden

— Clypeus with free margin only weakly reflexed; antennal club about 1.5 times as long as funicle; pronotal disc glabrous; body length usually under 5 mm; west of La Paz ................................. ..................................................................................................................... A. parva Howden

20(16). Hairs on elytral disc conspicuous, at least some as long or longer than the width of elytral intervals; color tan to dark brown .......................................................................................................... 22

— Hairs on elytral disc shorter and inconspicuous even when fresh, most no longer than width of a discal elytral interval; color light tan to tan .......................................................................... 21

21(20). Clypeus distinctly emarginate, bidentate when fresh; labrum very small, scarcely elevated above ventral surface of clypeus (length usually 1/6 th or less of clypeopleural length (underside of adjacent clypeus) at middle, narrowest ventral interocular distance distinctly less than half of maximum ventral eye width ( Fig. 18 ); generally distributed in Sonoran Desert of Arizona (expected in northwest Sonora) ............................................................... A. arizonica Brown

— Clypeus rounded or truncate; labrum larger, tumid, its length usually 1/5 th to 1/4 th medial clypeoplural length, narrowest ventral interocular distance more than half of maximum ventral eye width ( Fig. 19 ); mostly Sonoran Desert of Pinal and eastern Pima Counties in Arizona .... ..................................................................................................................... A. mixta Howden

22(20). Frontoclypeal transition scarcely tumid, frons rather evenly finely rugulose and granulate, with 2 vague tubercles in front of the posterior glabrous area; a pronounced ridge present above each eye; Durango, Mexico ( parva may also key here except for range) ............................................. ........................................................................................................ A. granulifrons Howden

— Frontoclypeal transition strongly tumidor frons irregularly, usually coarsely sculptured, or both; found north or west of Durango ............................................................................................. 23

23(22). Not occurring in Baja California; frons deeply, irregularly sculptured or conspicuously tumid near clypeus or both; median transverse band of spines on mesothoracic tibiae usually numbering 9 or less ................................................................................................................................... 24

— Vicinity of Mesquital , Baja California Sur ; frons finely, irregularly sculptured, evenly convex to nearly flat; median transverse band of spines on mesothoracic tibia usually numbering 10 or more .......................................................................................................... A. ochlera Howden

24(23). Pronotum with at least 1 to few discal hairs; Chihuahua ........................................................ 25

— Pronotal disc completely glabrous (hairs on margin only); distribution various but not recorded to date from Chihuahua .............................................................................................................. 26

25(24). Length usually over 5 mm; color reddish-brown; usually more than 8 setae on pronotal disc; near the Big Bend of the Rio Grande River (Ojinaga) .................................... A. seticollis Howden

— Size smaller, length usually 5 mm or less ; color dark brown; usually only 2-8 setae on pronotal disc ( Fig. 20 ); inland Chihuahua, far from Big Bend ................................. A. minuta Cazier

26(24). Clypeus usually distinctly emarginate, more or less bidentate ................................................ 27

— Clypeus usually more or less rounded to weakly emarginate apically, not distinctly bidentate ... ................................................................................................................................................ 28

27(26). Frontoclypeal transition distinctly tumid (best viewed from about 45 o posterior view), the tumosity extending into about the basomedial third of clypeus; western New Mexico and Arizona ......... .................................................................................................................... A. knulli Howden

— Frontoclypeal transition at most weakly tumid, not or only slightly extending onto more or less evenly cupuliform clypeus ( Fig. 23 ); dunes in El Paso, Texas, area ......... A. brunnea Casey

28(26). Big Bend area of Texas ; clypeus nearly parabolic, only vaguely flattened or weakly emarginate (if at all) apically ...................................................................................... A. conjuncta Howden

— Central Arizona to SE New Mexico; clypeus subrhomboidal to subpentagonal, apical margin weakly to distinctly sinuate on each side of medial weak to subdistinct emargination .................... 29

29(28). Frons deeply reticulate ( Fig. 21 ) ; color brown; size small, ranging between 4.5 and 5.7 mm; Dona Ana County, New Mexico .................................................................... A. diminiata Howden

— Frons shallowly reticulate; color tan; size moderate, usually larger, ranging between 5.8 and 6.6 mm; vicinity of Casa Grande, Arizona ....................................................... A. rufula Howden

Figures

Figure 14-17. Acoma spp. 14-15) Acoma robusta Van Dyke: 14) Head and pronotum. 15) Antenna. 16-17) Acoma sexfoliata Saylor: 16) head and pronotum. 17) Antenna.

Figure 10-13. Acoma quadrilaminata Warner: 10) Dorsal habitus. 11) Antenna. 12) Paramera. 13) Dorsolateral view of head and pronotum.

Figure 20-23. Heads and antennae: 20) Acoma minuta Cazier, paratype. 21) Acoma diminiata Howden, topotype. 22) Acoma mimica Howden, paratype. 23) Acoma brunnea Casey.

Figure 6-9. Acoma spp. 6-7) Acoma howdenorum Warner: 6) Dorsal habitus. 7) Antenna. 8-9) Acoma glabrata Cazier (specimen from Algodones Dunes): 8) Dorsal habitus. 9) Antenna.

Figure 1-5. Acoma spp. 1) Acoma glabrata Cazier, head and pronotum. 2-5) Acoma westcotti Warner: 2) Head and pronotum, 3) Dorsal habitus. 4) Left anterior tibia. 5) Pygidium.

Figure 26-27. Acoma cimarron Warner: 26) Head. 27) Paramera.

Figure 24-25. Acoma cimarron Warner, holotype: 24) Dorsal habitus. 25) Metatibia.

Figure 18-19. Ventral views of head showing mouthparts: 18) Acoma arizonica Brown. 19) Acoma mixta Howden.