Flea beetles of the West Indies: the genus Hemilactica Blake, 1937 (Coleoptera, Chrysomelidae, Galerucinae, Alticini)

The West Indian flea beetle genus Hemilactica Blake, 1937 is reviewed. Two new species, both from the Dominican Republic are described and illustrated: H. erwini sp. nov. and H. sierramatringarcia sp. nov. In addition, images of the holotypes of H. portoricensis Blake, H. pulchella Blake, and H. rugosa Blake are provided. Lactica megaspila (Blake) is transferred to Hemilactica. A lectotype of H. quatuordecimpunctata (Suffrian, 1868) is designated and illustrated, and a key to the Hemilactica species and a key for identification of Hemilactica and related genera occurring in the Western Hemisphere are provided.


Introduction
As of the most recent account, there are approximately 10,000 valid flea beetle species (Coleoptera: Chrysomelidae: Galerucinae: Alticini) assigned to 599 valid genera in the World. These constitute the most species-rich family level taxon in leaf beetle family and of these, 59 valid genera and 384 valid species are known to occur in the West Indies. Seventeen genera are West Indian endemics, including Hemilactica Blake, 1937. The genus contains nine species, with seven species known from Cuba, one from Puerto Rico, and one from the Dominican Republic. Two new species have been discovered in the Dominican Republic. They are described below.

Materials and methods
Dissecting techniques and morphological terminology follow Konstantinov (1998).
Specimen observations were made with a Zeiss Stemi SV11 Apo microscope. Digital photographs of morphological structures were taken with Axio Zoom V16 microscope and AxioCam HRC digital camera attached to it and with AxioCam HRC Zeiss attached to Leitz Dia plan compound microscope. Additional images were taken with Macropod Pro photomacrography system (Macroscopic Solutions, LLC, Tolland, CT, USA). Specimen labels are cited verbatim, according to the format justified previously (Konstantinov 1998;Konstantinov and Lingafelter 2002;Konstantinov et al. 2011).
Remarks. While describing the genus, Blake compared it with Lactica Erichson and Diphaulaca Chevrolat. It is indeed similar externally to both. However, Hemilactica specimens are missing sclerotized vaginal palpi as Lactica and related genera (Viswajyothi and Konstantinov 2020). The type species of Diphaulaca [D. aulica (Olivier)] has vaginal palpi well sclerotized and fully visible. Because of the structure of on the beetle's head sulci and ridges, the grooves on the pronotum and general body shape, Hemilactica generally fits into the Monomacra group of genera as roughly defined by Bechyne and Springlova de Bechyne (1975) and described in more details in Viswajyothi and Konstantinov (2020). In order to facilitate identification of Hemilactica, a key to it and related genera previously published (Viswajyothi and Konstantinov 2020) is provided at the end of the paper.
Currently known Hemilactica species exhibit some noticeable differences in "genus" level characters as they are currently understood for the purpose of revising flea beetle genera of the West Indies. The type species, H. pulchella and H. rugosa Blake are quite similar in having strongly punctate dorsum and relatively long and narrow frontal ridge, while species that Blake (1964) described later (e.g., H. portoricensis) have a much shorter and wider frontal ridge and smooth elytra with much smaller elytral and pronotal punctations. However, the other substantial features of these beetles look similar. Therefore, they are all retained under Hemilactica until more evidence comes to light. Lactica megaspila Blake (Fig. 26) is clearly congeneric with Hemilactica portoricensis and therefore is transferred here to Hemilactica. Diagnosis. Pronotum with two longitudinal dark spots on both sides of middle. Elytron with following dark spots: one on humeral callus, one medially to it, on basal callus, one below basal callus towards middle of elytron, one laterally towards side of elytron. Spots vary in size and color, some barely visible. Supracallinal sulcus poorly developed, straight, or convex, perpendicular to midline. Frontal ridge relatively long, dorsally wider than ventrally. Receptacle of spermatheca with inner side straight, outer side convex. Median lobe of aedeagus in lateral view bends abruptly about middle, with tip curving dorsally. Median lobe in ventral view more or less parallel sided basally, narrowing gradually towards narrow apex, lacking denticle.
Description. Body length 3.02-3.29 mm. Body width (widest point of elytra) 1.56-1.62 mm. Body height 1.08-1.13 mm. Pronotum and elytron yellowish, straw color with poorly defined, brownish spots. Pronotum with two longitudinal spots on both sides of middle. Elytron with following spots: one on humeral callus, one medially to it, on basal callus, one below basal callus towards middle of elytron, one laterally towards side of elytron. Spots vary in size and color, some barely visible (Fig. 2). Head. Surface of vertex densely and evenly covered with large punctures (Fig. 5). Orbit reduced to a narrow grove between eye and antennal callus. Supraorbital pore well developed, noticeable among other punctations. Inner margins of eyes slightly concave to straight, diverging towards mouth parts. Distance between eyes above antennal sockets in frontal view slightly greater than transverse diameter of eye. Sides of head below eyes converging ventrally. Anterior margin of labrum entire. Labrum with two pairs of setae placed symmetrically on sides. Midcranial suture absent. Supraorbital sulcus represented by fold between antennal callus and orbit. Orbital sulcus well developed. Supracallinal sulcus poorly developed, straight, or convex, perpendicular to midline. Supracallinal and supraorbital sulci form wide angle. Midfrontal sulcus well developed, long. Suprafrontal sulcus well developed, antennal calli and top of frontal ridge meet, separated by groove. Antennal calli nearly trapezoidal or nearly quadrate, directed longitudinally, not entering interantennal space. Frontal ridge relatively long, dorsally wider than ventrally. Its sides between antennal sockets slightly concave. Dorsal side of frontal ridge acute. Frontal ridge extends slightly between antennal calli. Anterofrontal ridge very low, merges with clypeus.
Prothorax surface glabrous, deeply and coarsely punctate (Fig. 6). Anterolateral callosity elongate, not expanded beyond lateral margin, facing anterolaterally. Anterior setiferous pore along anterolateral callosity situated close to posterior end. Anterolateral corners of pronotum projected slightly forward. Sides of pronotum slightly and evenly convex more so anteriorly. Base of pronotum with two short impressions visible only near basal margin. Pronotal base evenly convex. Antebasal transverse impression on pronotum shallow and poorly defined, better visible near longitudinal impressions, limited by them. Posterolateral callosity situated on corner of posterior and lateral margins. Procoxal cavities open. Intercoxal prosternal process convex at apex, extends beyond procoxae.
Legs. Pro-and mesotibiae without apical spur and with longitudinal ridge. Protarsomere 1 in males wider and longer than in females. Metatibia (Fig. 8) straight in dorsal view, slightly curved in lateral view, more or less cylindrical around middle. Metatibia on lateral side without small denticles. Metatibial apex flattened dorsally before tarsal insertion. Metatibial spur simple, narrow, ending in one tooth, situated laterally, nearly as long as greatest width of metatibial apex. Incision of metatarsomere 3 present. Claw appendiculate with a short lobe.
Genitalia. Spermatheca ( Fig. 9) with receptacle and pump with distinct border in between. Receptacle longer than wide, in a single plane, inner side straight, outer side convex, longer and wider than pump. Pump more or less straight. Duct of spermatheca without coils, roundish, narrowing abruptly towards gland. Vaginal palpi absent. Tignum narrow anteriorly into a narrow lobe (Fig. 11). Median lobe of aedeagus ( Fig. 10) bends abruptly about middle, with tip curving dorsally in lateral view. In ventral view more or less parallel-sided basally, narrowing gradually towards narrow apex, lacking denticle.
Habitat. Seasonally dry tropical forest.
Etymology. This species is named after Terry L. Erwin, USNM Coleoptera curator, prolific ground beetle systematist, and pioneering scholar of tropical biodiversity. Comments. Hemilactica erwini is similar to the type species of the genus, H. pulchella Blake and H. rugosa Blake in having relatively narrow frontal ridge and deeply and coarsely punctate elytra with brownish, poorly defined spots and lacking ridges. Diagnosis. Pronotum, thorax, antennae, and legs uniformly orange, with tips of legs a bit darker. Elytra uniformly blue. Supracallinal sulcus poorly developed, straight, or convex, perpendicular to midline. Midfrontal sulcus visible, long, but weakly impressed. Frontal ridge relatively long, dorsally wider than ventrally. Median lobe of aedeagus bends gradually about middle, with tip curving dorsally in lateral view. Spermathecal pump more or less straight, wider than receptacle, with small round structure at the tip.
Description. Body length 2.16-2.70 mm. Body width (widest point of elytra) 1.13-1.51 mm. Body height 0.81-0.86 mm. Pronotum, thorax, antennae, and legs uniformly orange, with tips of legs a bit darker. Elytra uniformly blue. Abdomen dark brown with tip a bit lighter.
Head. Surface of vertex densely and evenly covered with large punctations (Fig. 15). Orbit narrow. Supraorbital pore well developed, noticeable among other punctations. Inner margins of eyes slightly concave to straight, diverging towards mouth parts. Distance between eyes above antennal sockets in frontal view three times greater than transverse diameter of eye. Sides of head below eyes converging ventrally. Anterior margin of labrum entire. Labrum with two pairs of setae placed symmetrically on sides of labrum. Midcranial suture absent. Supraorbital sulcus represented by fold between antennal callus and orbit. Orbital sulcus poorly developed. Supracallinal sulcus poorly developed, straight, or convex, perpendicular to midline. Supracallinal and supraorbital sulci form wide angle. Midfrontal sulcus visible, long, but weakly impressed. Suprafrontal sulcus long, antennal calli and top of frontal ridge meet, separated by groove. Antennal calli nearly trapezoidal or nearly quadrate, directed longitudinally, not entering interantennal space. Frontal ridge relatively long, dorsally wider than ventrally. Its sides between antennal sockets slightly convex. Dorsal side of frontal ridge acute. Frontal ridge extends slightly between antennal calli. Anterofrontal ridge very low, merges with clypeus.
Prothorax surface glabrous (Fig. 14), covered with relatively shallow, sparsely placed punctations. Anterolateral callosity elongate, not expanded beyond lateral margin, facing anterolaterally. Anterior setiferous pore along anterolateral callosity situated close to posterior end. Anterolateral corners of pronotum projected slightly forward. Sides of pronotum slightly and evenly convex. Base of pronotum with two short impressions visible only near basal margin. Pronotal base evenly convex. Antebasal transverse impression on pronotum shallow and poorly defined, better visible near longitudinal impressions, limited by them. Posterolateral callosity situated on corner of posterior and lateral margins. Procoxal cavities open. Intercoxal prosternal process convex at apex, extends beyond procoxae.  Elytra at base wider than base of pronotum, with convex sides. Humeral and basal calli present. Elytral punctation confused. Punctations deeper and slightly larger than those of pronotum. Ridges on elytra absent (Fig. 13).   Legs. Pro-and mesotibiae without apical spur and with longitudinal ridge (Fig. 21). Protarsomere 1 in males wider and longer than in females. Metatibia straight in dorsal view, slightly curved in lateral view, more or less cylindrical around middle. Metatibia on lateral side without small denticles (Fig. 20). Metatibial apex flattened dorsally before tarsal insertion. Metatibial spur simple, narrow, ending in one tooth, situated laterally, nearly as long as greatest width of metatibial apex. Incision of metatarsomere 3 present. Claw appendiculate with a short lobe.
Genitalia: Spermatheca with receptacle and pump with distinct border in between (Fig. 24). Receptacle longer than wide, in a single plane, inner side straight, outer side convex, longer and narrower than pump. Pump more or less straight, wider than receptacle, with small oval structure at the tip. Duct of spermatheca without coils, roundish, narrowing abruptly towards gland. Vaginal palpi absent. Tignum widens anteriorly into a wide lobe (Fig. 23). Median lobe of aedeagus in lateral view bends gradually at about middle, with tip curving dorsally. In ventral view slightly constricted basally and above middle basally, lacking denticle (Fig. 22).
Habitat. Seasonally dry tropical forest (Franklin et al. 2019). Etymology. Specific epithet is a noun in apposition based on the type locality, Sierra Martin Garcia.
Comments. Hemilactica sierramartingarcia is quite unusual among Hemilactica species because its uniformly blue elytra. Among them it is similar to H. stomachosa (Suffrian), which elytra are also bluish. The concept of H. stomachosa is based on the specimen from Cuba that Blake identified as such with "?". Both species may be separated by weakly developed pronotal grooves in H. sierramartingarcia. Pronotal grooves are well developed in H. stomachosa. Hemilactica sierramartingarcia is similar to the type species of the genus, H. pulchella Blake, H. erwini, and H. rugosa Blake in having deeply and coarsely punctate and lacking elytral ridges. Interestingly, median lobe of aedeagus in H. sierramartingarcia and in H. erwini have an elongate apex strongly bent dorsally (Figs 10, 22), which may be a character that identifies the genus. Hemilactica sierramartingarcia may be separated from them by the smaller size and the body color. In addition, H. sierramartingarcia may be identified with the help of the key below. Elytron with eight dark brown spots: one on basal callus, one on humeral callus, three spots across elytron near middle, and three above elytral apex (Fig. 29)  Most of pronotum dark brown. Apex of median lobe of aedeagus produced into a long, thin projection slightly widening at the apex (Fig. 30) Most of pronotum yellowish. Apex of median lobe of aedeagus produced into a relatively short projection not widening at the apex (Fig. 2)  Elytron dark yellow to orange with wide, bright greenish blue bands basally and apically (Fig. 25)  Pronotum and elytra entirely yellowish to orange, lacking markings, except bases of elytra slightly darker (Fig. 26)  Elytron with multiple longitudinal ridges and merging dark spots at base in middle and apex (Fig. 28)  Front and mid tibiae yellow. Basal and apical elytral spots more or less roundish (Fig. 27)  suggestions as well as James Liebherr (Cornell University, Ithaca, NY) and Nathalie Yonow for handling the editorial process of this paper. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA; the USDA is an equal opportunity provider and employer.