Mordellina washingtonensis Steury and Steiner, 2020

Steury, Brent W. & Steiner, Warren E., 2020, Descriptions of Four New Species of Tumbling Flower Beetles (Coleoptera: Mordellidae) from Eastern North America, The Coleopterists Bulletin 74 (4), pp. 699-709 : 702-704

Mordellina washingtonensis Steury and Steiner , new species

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( Figs. 2D , 3D , 5A–B )

Type Material. Holotype. Male ( USNM), labeled “Virginia, Fairfax Co., GWMP, Dyke Marsh Wildlife Preserve, Malaise trap, 15–30 May 1998, E. Barrows. ” Paratypes (n = 23). One paratype, male ( USNM), labeled “Virginia, Fairfax Co., GWMP, Great Falls Park , Mine Run , Malaise trap, 16–30 July 2009, D. Smith. ” Additional paratypes, all male ( GWMP), all labeled “ Virginia , Fairfax Co. , GWMP ” and “ Turkey Run Park , floodplain forest, Malaise trap, 23 May–5 June 2008, D. Smith ” (n = 2); “ Turkey Run Park, gulch, Malaise trap, 7–21 June 2006, D. Smith ” (n = 2); same data but 1–15 July 2009 (n = 1) ; “ Great Falls Park , Mine Run , Malaise trap, 16–30 July 2009, D. Smith ” (n = 1); “ Great Falls Park, swamp, Malaise trap, 15–29 June 2006, D. Smith ” (n = 1); “ Little Hunting Creek, Malaise trap, 2–20 June 2017, B. Steury, C. Acosta, C. Davis ” (n = 2); “Dyke Marsh Wildlife Preserve, Malaise trap, 6–20 June 1999, E. Barrows ” (n = 5); same data but “ 20 June–2 July 1999 ” (n = 1); “ 24 June–7 July 1998 ” (n = 2); “ 7–19 July 1998 ” (n = 3); “ 19–30 July 1998 ” (n = 1).

Description. Holotype, male. Body length 3.3 mm to tip of elytra, 3.9 mm to tip of pygidium. Dorsal habitus narrow, unicolorous pale brown. Ventral habitus color as above but ventrites 1–3 black, 4 black apically, pale brown below. Pygidium slender, concolorous with dorsum, 2.7× length of hypopygidium. Pubescence dorsally and ventrally recumbent, pale, slightly shorter on head and pronotum than on elytra. Eyes emarginate behind the antennae, with many short, erect hairs, temple absent. Antennae ( Fig. 2D ) yellowish, slender, filiform, setaceous, antennomeres 3 and 4 the shortest and subequal, 1 and 2 subequal, each longer than 3 or 4, 5 longer than 3 and 4 combined, 5–11 becoming slightly, progressively longer, 11 the longest. Terminal maxillary palpomeres scalene, the lateral margin the longest. Pronotum broadest just before arcuate base, the midbasal lobe truncate or slightly indented at middle, lateral margin shallowly sinuate with apex near base. Scutellar shield small and triangular. Elytra together 2.5 times as long as broad at widest point, narrower at base than pronotum, sides subparallel on basal two-thirds, rounded at apex. Legs: Protibia of male expanded ( Fig. 3D ), widest at apical and basal third, with dense patch of black setae at apical third and sparse row of thin, erect, black setae on lateral margin; protarsomere 1 bowed and expanded apically with a few erect black setae on apical dorsal margin; metatibia with one subapical and two lateral ridges, the proximal lateral ridge much longer, extending nearly across the tibia, two metatibial spines, the outer one-third the length of the inner one; metatarsomere 1 with three short ridges, metatarsomere 2 with two short ridges; pro- and mesotarsomeres 4 truncate at apex.

Probable Females. Differing from males in having the ventrites all pale, shorter antennomeres 5–11, and unexpanded protibia. Specimens (n = 9, GWMP): All labeled “Virginia, Fairfax Co., GWMP” and “ Turkey Run Park, gulch, Malaise trap, 22 June–6 July 2006, D. Smith ” (n = 3); same data except, “river trail, 31 July–17 August 2009 ” (n = 3); “floodplain forest, 7–21 June 2006 ” (n = 1); same data except “21 July–4 August” (n = 1); “Dyke Marsh Wildlife Preserve, forest, Malaise trap, 1–15 August 1998, E. Barrows ” (n = 1).

Diagnosis. Mordellina washingtonensis has a dorsal habitus similar to Mordellina testacea (Blatchley, 1910) ( Figs. 6A–B ) but it has a darker brownish cuticle when compared to the yellowish color of fresh M. testacea . Additionally, it differs from M. testacea by the expanded male protibia which has a dense patch of black setae at the apical third with a sparse row of thin, erect, black setae on the lateral margin, and protarsomere 1 that is bowed and expanded apically, with a few erect black setae apically ( Fig. 3D ). The protibia of M. testacea is half the width of M. washingtonensis , lacks the black setal patch, is widest at the middle, narrowing to the base and apex, and protarsomere 1 is not bowed and is of uniform width ( Fig. 3C ). Additionally, antennomeres 5–11 are more than twice as long in M. washingtonensis as in M. testacea ( Figs. 2C–D ). Mordellina washingtonensis is also similar to the western species Mordellina wickhami Liljeblad, 1945 , but this species has the protibia and protarsomere 1 nearly identical to M. testacea . It differs from M. testacea in having a darker epidermis (slightly darker than M. washingtonensis in the aged holotype), has apically dark ventrites 1–4 (as in M. washingtonensis ), and has darker antennae than either species.

Variation. Length 2.8–3.4 mm to tip of elytra, 3.2–4.0 mm to tip of pygidium.

Etymology. Mordellina washingtonensis is named in honor of the National Park where the type specimens were collected, the George Washington Memorial Parkway, and thus indirectly for George Washington, first president under the Constitution, for whom the parkway is named.

Biology. Mordellina washingtonensis is currently known from 23 male specimens and nine probable female specimens collected from a National Park, George Washington Memorial Parkway, in Fairfax County, Virginia. It occurs on the Coastal Plain (16 specimens) and the Piedmont (Potomac Gorge) physiographic provinces in deciduous, riverine forest. Specimens were collected in Malaise traps set during 15 May–30 July (males) and 7 June–17 August (probable females).

Comments. The two species described above are morphologically distinctive in North America in having the male protibiae expanded, paddle-like, with patches of stiff setae on the dorsal side. These are presumably secondary sexual features, similar to those seen in other beetle groups and often in all legs (modified with curves, teeth, hair brushes, etc.) yet unmodified in the females. Two other New World species, currently placed in Mordellistena Costa, 1854 , are known to have similarly widened front tibiae: Mordellistena distorta Champion, 1891 from Nicaragua and M. curvimana Champion, 1891 from Guatemala.Both are illustrated in Champion (1890 –1893: table XV, figs. 16–17).

Figures

Fig. 2. Antennae of Mordellina species. A) M. ancilla, B) M. wimbledon, new species, C) M. testacea, D) M. washingtonensis, new species.

Fig. 3. Mordellina species, right front legs of males. A) M. ancilla, B) M. wimbledon, new species, C) M. testacea, D) M. washingtonensis, new species.

Fig. 5. Mordellina washingtonensis, new species, holotype, male. A) Dorsal, B) Lateral. Virginia, Fairfax County, GWMP, Dyke Marsh Wildlife Preserve, Malaise trap, 15–30 May 1998, E. Barrows. Length 3.3 mm to tip of elytra, 3.9 mm to tip of pygidium.

Fig. 6. Mordellina testacea, male. A) Dorsal, B) Lateral. Virginia, Fairfax County, Great Falls Park, swamp, Malaise trap, 1–19 July 2009, D. Smith and B. Steury. Length 3.2 mm to tip of elytra, 3.8 mm to tip of pygidium.