Scarites stenops Bousquet and Skelley

Bousquet, Yves & Skelley, Paul E., 2010, DESCRIPTION OF A NEW SPECIES OF SCARITES FABRICIUS (COLEOPTERA: CARABIDAE) FROM FLORIDA, The Coleopterists Bulletin 64 (1), pp. 45-49 : 46-48

Scarites stenops Bousquet and Skelley , new species

( Fig. 1 )

Type Material. Holotype (♂) labelled: “ FLORIDA: Levy Co. 4.0 mi. SW Archer on Rt-24: 15.VIII-28- IX-2000: P.E. Skelley burrow intercept trap / Holotype Scarites stenops Bousquet & Skelley. ” The holotype is deposited in the Florida State Collection of Arthropods.

Etymology. The specific name comes from the Greek stenos (narrow) and ops (eye) in reference to the small, narrow eyes of the adults.

Diagnosis. This species is unique among Scarites members for the unusually small and flat eyes.

Description. Coloration. Body reddish brown; antennomeres 2-11, trochanters, and tibiae reddish, femora reddish brown. Microsculpture. Frons medially without distinct meshes. Pronotum without distinct meshes on disc; base with irregular isodiametric meshes, sculpticells more or less convex; lateral depressions with isodiametric meshes, sculpticells flat. Elytra with irregular isodiametric meshes on apical fourth and in and around striae on basal three-fourths. Proepisternum and prosternum (except medially) with irregular isodiametric meshes, sculpticells slightly convex. Abdominal sternites with irregular isodiametric meshes over entire surface, sculpticells slightly convex in spots. Head. Proportionally wide, 0.96 times maximum width of pronotum. Eyes reduced, flat; postocular area projecting laterad beyond eye, with faint ocular ridge. Antennomeres 8–10 as broad as long; antennomere 1 as long as antennomeres 2–5 combined. Pronotum. Widest in front of middle, without midlateral setae. Elytra. Elongate-ovate, widest slightly behind middle, about 1.8 times longer than wide. Striae impressed, except near apex, impunctate; intervals 1–6 very slightly convex, interval 7 markedly convex in basal third; interval 3 with 2 setigerous punctures located in apical third. Pustulate area at base extending to apex of humeral carina, and laterally covering entire inflexed part of elytron. Thorax (ventral). Prosternum convex medially, without slight depression before prosternal apophysis. Prosternal apophysis glabrous. Metasternum, behind mesocoxa, slightly shorter than length of metacoxa along same line; without setigerous puncture. Metepisternum relatively short, its anterior edge about 0.55 times the lateral edge. Wings. Reduced. Legs. Lateral edge of protibia with 4 distinct indentations, each with a seta, before large preapical acute protuberance. Male genitalia. No obvious difference from S. subterraneus . Length. Apparent body length 9.2 mm; left elytron length 6.10 mm (to the nearest 0.05 mm).

Distribution. Scarites stenops is known only from the type locality. It is sympatric with S. subterraneus , S. marinus , and possibly S. ocalensis which is known from neighboring Alachua County ( Nichols 1986a).

Relationships. Scarites stenops is most similar in external structures to S. marinus and S. ocalensis and is probably closely related to them. Relationships between the three species cannot be addressed at this time.

Habitat and Collecting Method. Florida is composed of numerous sand ridge systems that were beach dunes formed by prehistoric fluctuations in ocean levels ( Webb 1990; Lamb et al. 2006). The separate origins and continued isolation of these ridge systems have allowed species to evolve independently so that each system has the potential for endemism. These ridges are often characterized by two different plant communities, called sandhill and scrub, which grow in deep, sandy, well drained soils. These upland plant communities are firemaintained and tend to have short vegetation with open patches of sand.

The type locality of S. stenops is part of the Northern Brooksville Ridge. The site has typical deep sandy soils and sandhill indicator plants including turkey oak ( Quercus laevis Walter : Fagaceae ), wiregrass ( Aristida stricta Michx. : Poaceae ), and longleaf pine ( Pinus palustris Mill. : Pinaceae ). However, the site also has numerous patches of Florida rosemary ( Ceratiola ericoides Michx. : Ericaceae ), a plant characteristic of beach dunes. It remains to be determined if S. stenops is restricted to the Northern Brooksville Ridge or not.

To collect dune-inhabiting insects, a collector must be lucky or know the factors limiting the insect’ s surface activity. That assumes the insect has periods of surface activity! Collectors must be present at the exact time of an emergence or need to employ laborious techniques such as sifting, raking, floating, excavation, etc., to obtain an occasional subterranean specimen. The second author experimented with various underground traps, “burrow intercept traps,” trying to sample for subterranean taxa over an extended period of time in the dune soils. One of these traps collected the only known specimen of S. stenops .

Similar to the principles behind Malaise traps for flying insects or fence traps for walking insects, burrow intercept traps guide burrowing insects to a collecting container. The general design of each trap was a pitfall in the bottom of a hole which was covered with a board. The hole became a cavity in the soil into which burrowing insects would fall. Different designs use wire mesh or other structures to support the walls of the hole, various metal barriers in the ground to act as fences, and several styles of collection containers.

Numerous subterranean beetles with greatly reduced eyes have been recently described, for example in the carabid genera Clivina Latreille ( Bousquet 1997; Ball 2001) and Anillinus Casey ( Sokolov et al. 2004), the scarab genus Geopsammodius Gordon and Pittino ( Skelley 2006) , and many additional diverse, often microscopic groups. These studies show that subterranean (nontroglodytic) insects are widespread and basically unknown. Considering the amount of time, effort, and money needed to build, deploy, and service the underground traps which ultimately collected one S. stenops , the costs per insect specimen were quite high. However, nearly all are rare in collections and some remain undescribed. We hope that other researchers will continue to use subterranean collecting methods and design a more productive passive subterranean barrier trap. We have only just begun to scratch the surface.

Remarks. Scarites stenops belongs to the subterraneus group of the subgenus Scarites s.str. as defined by Nichols (1986a), in which members are characterized by having antennomeres 8– 10 moniliform. The group includes the New World Scarites alternans Chaudoir S. subterraneus , S. marinus , and S. ocalensis . Scarites ocalensis is precinctive to the Florida Peninsula north of Lake Okeechobee; S. marinus is known from coastal Florida, including the Keys, the Bahamas, Cuba, and the Yucatán Peninsula, and S. alternans is precinctive to Cuba. Scarites subterraneus is widely distributed from southeastern New Hampshire to eastern North Dakota, including southern Ontario ( Lindroth 1961), south to the Yucatán Peninsula ( Nichols 1988a), the Florida Keys (Peck and Thomas 1998), and Cuba ( Darlington 1934; Nichols 1988b), west along the southwest to southwestern California (LeConte, 1852, as S. californicus LeConte ) and Baja California ( Horn 1894).

Bousquet and Larochelle (1993) listed four other species of Scarites for the North American fauna (north of Mexico): S. lissopterus Chaudoir , S. patruelis LeConte , S. quadriceps Chaudoir , and S. texanus Chaudoir. Nichols (1988a) , in his unpublished Ph.D. thesis, retained S. patruelis as a junior synonym of S. subterraneus and, based on a study of the type material he made, listed S. texanus as a junior synonym of S. subterraneus [new synonymy], which is validated here.

Nichols (1986b) retained three species of Scarites , besides those of the subterraneus group, in the North American fauna: S. vicinus , S. lissopterus , and S. quadriceps . He separated the latter two species by their size and distribution: S. lissopterus being smaller (hindbody less than 13.0 mm in length) and distributed west of the Mississippi River, including the Rio Grande drainage, while S. quadriceps is larger (hindbody greater than 13.0 mm) and distributed along the Atlantic coast and in the Gulf Coastal Plains. From an examination of more than one hundred specimens, we found that the body size does not clearly correlate with distribution and cannot be used to confidently separate these two entities. For this reason, at this time we recognize only two other species of Scarites in North America north of Mexico, in addition to those species in the subterraneus group: S. vicinus [revised status] and S. quadriceps . These two species belong to the quadriceps group and have antennomeres 8–10 longer than wide.

Following is a key to the species of Scarites found in North America north of Mexico. All species belong to the subgenus Scarites s. str., which differs from the other Western Hemisphere subgenus of Scarites , Taeniolobus , in having the last four visible abdominal sterna each without a basal transverse groove.

KEY TO NORTH AMERICAN (NORTH OF MEXICO) SPECIES OF SCARITES

1. Antennomeres 8–10 longer than wide, length/ width of antennomere X = 1.1–1.3 [ quadriceps group]....................................................2

– Antennomeres 8–10 wider than long or subquadrate, length/width of antennomere X = 0.8–1.0 [ subterraneus group].............3

2. Metasternum proportionally shorter, LMs / LMc = 0.98–1.02 .......... S. vicinus Chaudoir

– Metasternum proportionally more elongate, LMs / LMc = 1.10–1.30 .................... .............................. S. quadriceps Chaudoir

3. Metasternum proportionally more elongate, LMs / LMc = 1.10–1.40. Wings fully developed [widely distributed in the United States and also in southern Ontario]............... ............................. S. subterraneus Fabricius

– Metasternum proportionally shorter, LMs / LMc = 0.75– 1.03. Wings reduced [in North America, north of Mexico, in Florida only]................................................................4

4. Eyes flat, head width at level of eyes smaller than at level of temples. Pustules at base of elytra more expanded, reaching level of humeral carina apex between intervals 2–4. Elytral interval 7 markedly convex, more or less cariniform, in basal third .......... .................................. S. stenops new species

– Eyes slightly to moderately convex, head width at level of eyes subequal or greater than width at level of temples. Pustules at base of elytra less expanded, distinctly not reaching level of humeral carina apex between intervals 2–4. Elytral interval 7 slightly convex or flat in basal third...........5

5. Metasternum proportionally more elongate, LMs / LMc = 0.98–1.03. Eyes more convex, head width at level of eyes greater than width at level of temples ....................... ....................................... S. marinus Nichols

– Metasternum proportionally shorter, LMs / LMc = 0.76–0.84. Eyes less convex, head width at level of eyes subequal to width at level of temples.............. S. ocalensis Nichols

Figures

Fig. 1. Habitus of Scarites stenops (dorsal view). Scale bar = 1 mm.