Macrosiphum mentzeliae Wilson, 1915

Jensen, Andrew S. & Rorabaugh, Jesse, 2020, New Macrosiphum Passerini (Hemiptera: Aphididae) Information From Western North America, Including One New Species And One New Synonymy, Proceedings of the Entomological Society of Washington 122 (1), pp. 81-103 : 92-102

Macrosiphum mentzeliae Wilson

( Figs. 13–24 )

Macrosiphum mentzeliae, Wilson 1915 :

99, Gillette and Palmer 1934: 188,

Palmer 1952: 316, Eastop and Hille Ris

Lambers 1976: 260, Smith and Parron

1978: 184, Remaudière, and Remaudière

1997: 115, Blackman and Eastop 2006:

1212.

Biology and distribution.—This

aphid was described by Wilson (1915)

based on a single sample of apterae and

alatae sent to him from Monclova,

Mexico, collected on “ Mentzelia ” in

November of 1909. Subsequently,

Palmer (1952) recorded collecting it on

“ Mentzelia sp.,” including oviparae and

alate males, indicating a monoecious life

cycle. Her specimens were from Colo-

rado and Utah and she reported that

it was “rather common.” The first au-

thor has also found it to be common

across western U.S.A. Blackman and

Eastop (2019) report the host plant as

“ Mentzelia aspera (= M. albicaulis ), and

possibly other Mentzelia spp.” (The ref-

erence to Mentzelia albicaulis (Douglas)

Douglas ex Torr. & A. Gray being a

synonym of Mentzelia aspera L. is apparently based on information provided by The Plant List (2019) but seems to conflict with accepted nomenclature. The second author consulted various online resources and a published checklist ( Villaseñor 2016) and could not find confirmation of this synonymy and we therefore use the name M. albicaulis hereafter.) Available specimens, all in the ASJ collection, have been collected from M. albicaulis , Mentzelia laevicaulis (Douglas) Torrey & A. Gray , and “ Mentzelia .” At least one of these samples was collected on a plant other than M. albicaulis and M. laevicaulis – a sample from near Socorro, New Mexico on a tall Mentzelia with large white flowers. It seems, therefore, that M. mentzeliae has a wide host range within Mentzelia .

This aphid is unusual in that it lives in a wide range of habitat types and exists across a huge geographical area. The first author has collected it in desert habitats such as central New Mexico and central Washington, but also on lower slopes of forested mountains in central Oregon, especially in areas disturbed by road-building and wild fire, and on Douglas Pass in western Colorado at 2,500 m elevation. The host plants of M.

mentzeliae in Washington and Oregon ( M. albicaulis and M. laevicaulis ) are drought tolerant and actively grow through the hottest and driest parts of the year. Unlike many aphids, which reproduce little or not at all during hot summer conditions and are mostly found on host plants in moderate microclimates, M. mentzeliae can often be found on M. laevicaulis mid-summer growing in southfacing road-cuts in the hottest of localities such as Franklin County, Washington (see Material examined, below). Our funda- trices of M. mentzeliae were all collected in late March on warm sandy slopes, indicating egg hatch must have occurred in late February or early March, earlier than most aphids in these localities.

The known distribution of M. mentzeliae includes Mexico at least as far south and east as Monclova (Coahuila state), north to central Washington. Its host plants M. albicaulis and M. laevicaulis both have been recorded from Canada (eFloras 2019), indicating that M. mentzeliae may exist in western Canada as well.

Remarks.—We offer new illustrations ( Figs. 13–24 ) and measurements ( Table 2 ) for M. mentzeliae to add to the contributions of Wilson (1915) and Palmer (1952), easing comparison of this and similar species. We also add the first measurements of the fundatrix.

Macrosiphum mentzeliae can be separated from M. glawatz and M. gaurae as explained above. Like M. glawatz , M. mentzeliae shares important features with M. garyreed . The two species are easily distinguished by the presence of robust spinules ventro-laterally on a.s. I of M. mentzeliae (absent in M. garyreed ), and the usual presence of prominent lateral tubercles in M. garyreed (very small or absent in M. mentzeliae ). The u.r.s./ metatarsal II ratios overlap for these two species, but the u.r.s. length in M. garyreed is more than 190 µm versus 142– 186 µm in M. mentzeliae .

Above we mentioned that a feature shared by M. mentzeliae , M. gaurae , and M. glawatz is “moderate length antennae.” By this we mean a general impression made by the species in life and on slides. We can illustrate this by comparison with one other species in North America with a long u.r.s. and membranous tergum in apterae: Macrosiphum aetheocornum Smith and Knowlton , which feeds on wild Geranium spp. in western North America. The u.r.s./metatarsal II ratio in this species is similar to M. mentzeliae and the others mentioned above, but M. aetheocornum has longer antennae, segment by segment (as given for apterae by Palmer 1952): a.s. III 850–1020 µm, a.s. IV 650–750 µm, a.s. V 580–690 µm, versus a.s. III 534–822 µm, a.s. IV 348–636 µm, a.s. V 324–570 µm in M. mentzeliae (and almost identical ranges in M. glawatz and M. garyreed ).

Material examined.—Collecting details of the specimens measured for the taxonomic comparison to M. glawatz and for Table 2 are as follows.

Fundatrices: Slide number AJ5418, U.S.A., Oregon, Malheur County, Leslie Gulch, ex Mentzelia , 24 March 2012, A.S. Jensen (2 ASJ); Slide number AJ5432, U.S.A., Idaho, Ada County, Swan Falls, ex Mentzelia , 31 March 2012, A.S. Jensen (1 ASJ).

Apterae: Slide number AJ9310, U.S.A., Oregon, Grant County, Hwy 395 ~m.p. 12C south of John Day , ex Mentzelia albicaulis , 23 June 2017, A.S. Jensen (3 ASJ); Slide number AJ3067, U.S.A., Washington, Franklin County, Mesa, ex Mentzelia laevicaulis , 25 June 2008, A.S. Jensen (2 ASJ); Slide number AJ5035, U.S.A., Washington, Lincoln County, Coffee Pot Lake, ex Mentzelia , 26 June 2011, A.S. Jensen (4 ASJ); Slide number AJ3858, U.S.A., Washington, Lincoln County, Coffee Pot Lake, ex Mentzelia laevicaulis , 4 July 2009, A.S. Jensen (2 ASJ); Slide numbers AJ7760, AJ7761, U.S.A., Oregon, Harney County, Steens loop south side, ex Mentzelia , 6 September 2014 (6 ASJ); Slide numbers AJ4662, AJ4663, U.S.A., New Mexico, Socorro County, E. of Socorro, ex Mentzelia , 19 September 2010, A.S. Jensen (5 ASJ); Slide numbers AJ3289, AJ3290, U.S.A., Washington, Franklin County, Mesa, ex Mentzelia laevicaulis , 24 September 2008, A.S. Jensen (6 ASJ); Slide number AJ7780, U.S.A., New Mexico, Sandoval County, Cabezon Trail, ex Mentzelia , 23 September 2014, A.S. Jensen (3 ASJ); Slide number AJ6888, U.S.A., Arizona, Coconino County, S-P Crater, ex Mentzelia , 26 September 2013, A.S. Jensen (3 ASJ); Slide number AJ6124, U.S.A., New Mexico, Sierra County, nr. Kingston, ex Mentzelia , 5 October 2012, A.S. Jensen (2 ASJ).

Alatae: Slide number AJ7977, U.S.A., Oregon, Crook County, Ochoco N.F. nr. Summit of Hwy 26, ex Mentzelia , 4 June 2015, A.S. Jensen (1 ASJ); Slide numbers AJ3063, AJ3064, AJ3065, AJ3066, U.S.A., Washington, Franklin County, Mesa, ex Mentzelia laevicaulis , 25 June 2008, A.S. Jensen (4 ASJ); Slide number AJ8620, U.S.A., Oregon, Lake County, Hwy 31 near Summer Lake , ex Mentzelia laevicaulis , 10 July 2016, A.S. Jensen (2 ASJ); Slide numbers AJ5887, AJ5888, U.S.A., Colorado, Garfield County, Douglas Pass, ex Mentzelia , 20 August 2012, A.S. Jensen (3 ASJ).

Figures

Figs. 13–14. Macrosiphum mentzeliae. 13, Head capsule and antennal segments I of aptera, dorsum. 14, Head capsule and antennal segments I of aptera, ventral surface.

Figs. 15–16. Macrosiphum mentzeliae. 15, Head capsule and antennal segments I of alata, dorsum. 16, Head capsule and antennal segments I of alata, ventral surface.

Figs. 17–20. Macrosiphum mentzeliae. 17, Aptera a.s. III. 18, Alata a.s. III. 19, Siphunculus of aptera. 20, Siphunculus of alata.

Figs. 21–24. Macrosiphum mentzeliae. 21, Cauda of aptera, ventral surface. 22, Cauda of aptera, dorsal surface. 23, Aptera u.r.s. 24, Aptera metatarsus.