Ellescus michaeli Lewis and Anderson, 2023

Lewis, Jake H. & Anderson, Robert S., 2023, A review of EllESCUS (Coleoptera: Curculionidae) in North America: new species and synonyms revealed through integrative taxonomy, The Canadian Entomologist (e 15) 155 (2023), pp. 1-27 : 6-7

Key to the species of Ellescus in North America (including E. scanicus )

* Note that E. scanicus was previously reported from North America; however, this is apparently erroneous because all examined Nearctic specimens labelled as E. scanicus were incorrectly identified. The species is included here for reference.

0a) First two ventrites depressed medially; apical with ventrite shiny, medial carina extending longitudinally, or with distinct medial swelling at tip (occasionally reduced or totally absent; Fig. 3A, B ). Apical two tergites sclerotised (viewing this character often requires relaxing and manipulating specimens). Rostrum shorter ............................................................... [Male]

0b) First two ventrites not distinctly depressed medially; apical ventrite unmodified. Only apical tergite sclerotised. Rostrum longer ....................................................................................... [Female]

1a) Males with glabrous carina extending longitudinally over middle of apical ventrite; not prominent at apex of ventrite ( Fig. 3A ). Metepisternum and lateral half of metaventrite densely punctate and covered with appressed white–yellow scales ( Fig. 3C ), or with metepisternum and lateral half of metaventrite not densely punctate or scaled, with cuticle in those regions mostly visible ( Fig. 3D ). Pronotum rarely with regions of discoloured scales laterally ( Fig. 4 ). Apex of aedeagus well rounded or subquadrate, not pointed ( Fig. 5A, B ). Internal sac without fully protruding basal V-shaped structures ( Fig. 5A, B ). Spermatheca without prominent basal projection ( Fig. 6A, B ) .................. 2

1b) Males with prominent swelling at apex of apical ventrite [reduced in some smaller specimens] ( Fig. 3B ) or without any swelling. Metepisternum and lateral half of metaventritenum not as densely punctate or scaled, cuticle in those regions mostly visible ( Fig. 3D ). Pronotum with regions of discoloured scales laterally [occasionally reduced or absent completely] ( Figs. 7–9 ). Apex of aedeagus ending in a rounded to sharp point ( Fig. 5C–E ). Internal sac with fully protruding basal V-shaped structures ( Fig. 5C–E ). Spermatheca with prominent basal projection ( Fig. 6C ) ................................................................................................................................ 3

2a) Metepisternum and lateral half of metaventrite densely punctate and covered with appressed white–yellow scales, cuticle in those regions mostly concealed ( Fig. 3C ). Apex of aedeagus subquadrate ( Fig. 5A ). Internal sac with distinct V-shaped structure. ( Fig. 5A ). Spermatheca smoothly curved, without basal sinuation and inwards pointing tip ( Fig. 6 ). ...................... E. scanicus ( Paykull, 1792) (European; not present in North America)

2b) Metepisternum and lateral half of metaventrite not as densely punctate or scaled, cuticle in those regions mostly visible and with interspaces shiny ( Fig. 3D ). Apex of aedeagus rounded ( Fig. 5B ). Internal sac lacking V-shaped structure (instead with hook-like structure and roughened tissue; Fig. 5B ). Spermatheca not smoothly curved but with basal sinuation and often with inward curved tip ( Fig. 6B ) ............................. E. bipunctatus (Linnaeus, 1758)

3a) Cuticle mixed in colour (red, black, yellow, brown; Figs. 7 , 8A, B , 9 ).....................................4

3b) Cuticle entirely red or pale yellow ( Fig. 8C, D ) .... 6 [Dissection of males usually required]

4a) Metaventrite not contrasting with black femora, tibiae, and rostrum ( Fig. 8A, B ). Elytral colouration diagnostic: dark with transverse bright orange band in apical half ( Fig. 8A, B ). Apex of aedeagus ending in broadly rounded tip; lateral edges of apex dorsoventrally flattened, with setae distributed along surface ( Fig. 5D ). Length 1.9–2.2 mm ......................... Ellescus michaeli Lewis and Anderson , new species (in part)

4b) Metaventrite black and contrasting with reddish-brown legs and apical half of rostrum ( Figs. 7 , 9 ). Elytral colouration variable but never as above ( Figs. 7 , 9 ). Apex of aedeagus more pointed; apex with two prominent tufts of setae ( Fig. 5C, E ). Length 2.0– 2.9 mm ..................................................................................................................................5

5a) Apex of aedeagus quadrate to rounded, dorsoventrally flattened, and ending in an abrupt, sharp point; lateral edges of aedeagus heavily sclerotised ( Fig. 5C ). Restricted to California and southern Oregon .......................................... Ellescus californicus (Casey, 1885) (in part)

5b) Apex of aedeagus rounded, not distinctly dorsoventrally flattened, and ending in a distinct point; lateral edges of aedeagus not as heavily sclerotised ( Fig. 5E ). Widespread across North America (although apparently absent from California and southern Oregon) ...................................................................... Ellescus ephippiatus (Say, 1831) (in part)

6a) Apex of aedeagus ending in broadly rounded tip; lateral edges of apex dorsoventrally flattened, with setae distributed along surface ( Fig. 5D ). Length 1.9–2.2 mm ........................................................ Ellescus michaeli Lewis and Anderson , new species (in part)

6b) Apex of aedeagus ending in sharp tip ( Fig. 5C–E ). Length 2.0– 2.9 mm ................................. 7

7a) Apex of aedeagus quadrate and coming to a distinct, sharp point; lateral edges heavily sclerotised ( Fig. 5C ). Restricted to California and southern Oregon ........................................................................... Ellescus californicus (Casey, 1885) (in part)

7b) Apex of aedeagus rounded, ending in a distinct point; lateral edges not heavily sclerotised ( Fig. 5E ). Widespread across North America (although apparently absent from California and southern Oregon) ............................................. Ellescus ephippiatus (Say, 1831) (in part)

Figures

Fig. 3. Morphological characters used to distinguish Ellescus in North America: A, glabrous carina extending longitudinally across last ventrite (male E. bipunctatus); B, swelling at the tip of last ventrite (male E. californicus, E. ephippiatus, and E. michaeli new species); C, metaventrite and metepisternum with dense, heavily appressed scales covering cuticle (found only in both sexes of E. scanicus); and D, metaventrite and metepisternum without dense, heavily appressed scales (Ellescus species other than E. scanicus).

Fig. 4. Ellescus bipunctatus (Linnaeus, 1758): A, lateral view of “scanicus” form; B, dorsal view of “scanicus” form, with alternating bands of white scales and strong band along elytral suture; C, lateral view of red and black specimen; D, dorsal view of red and black specimen; E, lateral view of dark specimen; and F, dorsal view of dark specimen.

Fig. 5. Aedeagi of Ellescus species: A, Ellescus scanicus; B, Ellescus bipunctatus; C, Ellescus californicus; D, Ellescus michaeli new species; and E, Ellescus ephippiatus.

Fig. 6. Spermatheca of Ellescus species: A, Ellescus scanicus; B, Ellescus bipunctatus; and C, Ellescus californicus. Note that E. ephippiatus and E. michaeli new species are not presented because the spermatheca of these species do not differ noticeably from that of E. californicus.

Fig. 7. Ellescus californicus (Casey, 1885): A, dorsal view and B, lateral view.

Fig. 8. Ellescus michaeli new species: A, dorsal view of typical specimen; B, lateral view of typical specimen; C, dorsal view of all-red specimen from Otter Tail Co., Minnesota, United States of America; and D, lateral view of all-red specimen from Otter Tail Co., Minnesota.

Fig. 9. Ellescus ephippiatus (Say, 1832): A, dorsal view of red specimen with conspicuous pattern of scales on elytra; B, lateral view of red, patterned specimen; C, dorsal view of piceous, dark specimen; D, lateral view of piceous, dark specimen; E, dorsal view of red and black specimen lacking conspicuous pattern on elytra; and F, lateral view of red and black specimen.