Brachypeplus habecki Cline and Skelley

Cline, Andrew R. & Skelley, Paul E., 2013, Discovery of new species and country records for the North American sap beetle fauna (Coleoptera: Nitidulidae), Zootaxa 3683 (2), pp. 101-116 : 110-112

Brachypeplus habecki Cline and Skelley , n. sp.

( Figs. 12–13 )

Material examined. Holotype ( TAMU) Ƥ - USA: TEXAS: Cameron Co. / Sabal Palm Grove Ref. (site 1) / 25.84799°N, 97.41881°W / V–7–21–2009, FIT-ground / palm for. King & Riley-1015 // TAMU-ENTO / X0842606 [bar code label] // Brachypeplus / sp. / Det. E.G. Riley, 2010 // HOLOTYPE / Brachypeplus / habecki / Cline & Skelley Des. 2012 [red type label].

Description. Overall, body elongate,>3 times as long as wide, and flattened. Length 3.9 mm, width 0.9 mm. Body distinctly unicolored with abdomen and thoracic ventrites dark brown to piceous. Surface sculpturing on dorsum distinct and consisting of “scale-like” microreticulations between punctures on the head, pronotum, and elytra. Body setation minute and only apparent at high magnification; entire surface glossy and shining ( Figs. 12– 13 ).

Head transverse (W:L = 1.6:1.0), with paired depressions across the anterior part of vertex and frontoclypeal area. Surface punctures circular to slightly elliptical, irregular, approximately 2 eye facet widths in size. Punctures smaller and more vaguely impressed anteriorly, and more densely distributed along lateral and posterior margins. Interspaces microreticulate with scale-like sculpturing, and approximately 0.5–1.0 puncture diameter apart. Antennal grooves present, convergent, and well-defined by medial and lateral carinae. Vertex flat to slightly concave with shallow depressions on each side of midline near frontoclypeal region. Temples present and prominent, extending slightly beyond posterior lateral edge of eye. Eyes prominent, finely faceted, interfacetal setae absent. Antennal club shape slightly ovate; club 0.30 length of segments 1–8 combined. Terminal antennomere shorter than previous two segments combined; apex of terminal segment acuminate. Scape “hunchbacked” with anterior margin distinctly convex and>2 times longer than to segment 2. Pedicel small, shorter than segment 3. Clypeolabral junction shallowly concave. Labrum with anterior margin broadly concave and bearing single median point. Maxillary palpi with terminal segment elongate and conical, longer than segments 1–2 combined. Labial palpi with terminal segment somewhat barrel-shaped and shorter than segments 1–2 combined. Mentum highly transverse with anterior margin broadly convex medially; surface punctuation consisting of fine minute punctures with some bearing short fine setae; interspaces smooth and shining no scale-like microreticulations present. Submentum with punctures similar to vertex of head with some bearing fine minute setae; surface sculpturing similar to that of mentum.

Pronotum overall subquadrate (W:L = 1.00:0.63), widest near middle, flat to faintly concave across disc. Anterior angles distinct, evenly rounded, not projecting. Posterior angles distinct, evenly rounded, not projecting. Lateral margins evenly arcuate to anterior and posterior angles. Anterior margin bisinuate with broadly convex medial region. Posterior margin bisinuate with broadly convex medial region. Prosternum with space between coxae and anterior margin 3 times width of procoxal process between coxae. Prosternal process slightly expanded posterior to procoxae; in lateral view flat over procoxae, posterior margin with no vertical face. Mesonotum with scutellum hemispherical; pubescence, surface punctation and sculpturing similar to that on pronotum. Mesosternum flat, at same level as metasternum; surface punctation consisting of minute punctures anteriorly and laterally, but disc smooth; surface sculpturing consisting of oblique lines on lateral regions. Meso-metasternal junction broadly concave. Metasternum overall transverse (W:L = 1.54:1.00); metasternal disc surface punctation and sculpturing similar to pronotum with punctures 1–2 diameters apart. Postcoxal lines of mesocoxae present, slightly diverging from coxal cavities, and faintly apparent along medial 0.5 of mesocoxae; no definitive axillary space formed. Elytra short, exposing all of pygidium and last 2, and small portion of third, visible tergites; lateral margins narrowly explanate; serially punctuate/striate with punctures similar to those on pronotum, punctures within rows separated by 1–2 puncture diameters and puncture rows separated by 2–3 puncture diameters; sculpturing similar to pronotum with scale-like microreticulations present throughout. Humeral angles prominent. Fine minute light colored setae associated with some punctures, as well as along lateral margin of elytra. Elytra not separately rounded, forming straight line at junction where each elytron meets.

Visible abdominal ventrite 1 projecting between metacoxae with broadly rounded apex. Metacoxal lines not apparent. Visible abdominal ventrites 2–4 not equal in length, with following relative lengths 1.7/2.4/2.7. Hypopygidium with posterior margin convex. Pygidium with posterior margin medially concave, and bearing small tubercles on edge.

Legs unmodified. Each femora canaliculate for reception of tibiae; widest near middle. Protibiae with short stout hair-like spines along inner margin in distal 0.5 of segment, and row of short spines present along apical margin near spurs; inner margin of protibiae slightly curved. Mesotibiae with row of short spines along apical margin extending proximally around outer apical angle in distal 0.1 of segment; inner margin straight. Metatibiae with row of short spines along apical margin extending proximally around outer apical angle in distal 0.2 of segment; inner margin straight. Tarsomeres 1–3 lobed with dense empodium ventrally possessing short setae and longer lateral seta; claws simple.

Female genitalia not dissected in unique holotype. Male unknown.

Diagnosis. Brachypeplus habecki differs from other members of the genus by possessing the following characters: scale-like body and leg microsculpture, reduced body setation, hemispherical scutellum, acute temples, and a labrum with a distinct medial point. This species appears most similar to B. glaber based on the following shared characters: diminutive size, reduced body setation, and similar surface microsculpture on the body proper. However, the identification key above separates the two species. These species are likely allied to B. staphylinoides Sharp based on the condition of the mentum, antennae, diminutive size and body setation, however that species does not possess the scale-like microreticulations of B. glaber and B. habecki . Brachypeplus staphylinoides is widespread throughout most of Central America ( Blackwelder 1945, Cline unpub. catalogue).

Variation. Only one specimen is presently known.

Geographic distribution. The species is known only from the type locality in southern Texas.

Biology. Label data indicates the species is found in association with Sabal mexicana Mart. stands, which only persists in southern Texas and northern Mexico.

Etymology. The specific epithet honors the late Dale H. Habeck. Dale was a specialist on larval Nitidulidae as well as larval Lepidoptera, and collected much of the preserved material of B. glaber that is present in many museums in North America. Dale was a good friend and colleague.

Discussion/Notes. Brachypeplus habecki may represent a link between B. glaber from the southeastern United States and B. staphylinoides from the Neotropics, or conversely, an extreme southern population of B. glaber that underwent isolation and subsequent speciation on a different palm host species. No phylogenies, or molecular datasets, of Brachypeplus are available to test either hypothesis. However, these three species do share characters that other Neotropical Brachypeplus do not, suggesting sister-group affinities. Performing a phylogenetic analysis for all 100+ species of Brachypeplus worldwide is beyond the scope of this paper, but would be an interesting avenue of research we hope others will pursue.

The following notes are derived from correspondence with Ed Riley of Texas A&M University. The “ Sabal Palm Grove ” where the new species was collected is now correctly called the “ Sabal Palm Grove Preserve ” and is managed by the Gorgas Foundation which is associated with the University of Texas at Brownsville. This spot is well known to beetle collectors, as it was a place that Schaeffer, Barber, Wickham and undoubtedly other early collectors visited at the turn of 20th century when they made trips to Brownsville. During that time period, the grove was known as the “San Thomas Plantation” and is cited on labels by these early collectors variously as “Brownsville, S. Tom.” or “San Thomas.” Most of these early collections are currently housed at the Smithsonian Institution.

This Sabal Palm Grove Preserve is now well known for being the largest and best preserved tract of the original Sabal palm forest ( Sabal mexicana Martius ) of extreme southern Texas, a forest type that was once considerably more extensive before agriculture and other landscape disruptions altered the local habitat. The total preserve is approximately 500 acres and the US Fish and Wildlife Service has purchased the surrounding farmland and revegetated much of the area over the past several years. The original core of old growth palms is quite small, and when first visited by Ed Riley in 1979 it was surrounded by farmland with almost no buffer.

The beetle project that yielded the new Brachypeplus species was in operation from late summer 2008 to spring of 2010 and was generally known as the “Lower Rio Grande Valley beetle project.” Flight intercept traps (and other passive traps) were operated in the old growth core of the palm grove sanctuary for three months during late summer–fall (2008, 2009) and three months during spring (2009, 2010). Brachypeplus habecki was collected from the spring collecting event in 2009.

Figures

FIGURES 12 – 14. Habitus images of North American Brachypeplus. (12) B. habecki n. sp., dorsal habitus; (13) B. habecki n. sp., ventral habitus; (14) B. glaber, dorsal habitus. Scale bar = 1 mm.