A review of the genus Scaponopselaphus Scheerpeltz (Insecta: Coleoptera: Staphylinidae)

Abstract Background The genus Scaponopselaphus Scheerpeltz was originally described to accommodate the species Trigonopselaphus mutator Sharp. New information In this paper, I review Scaponopselaphus and describe a new species from Colombia as Scaponopselaphus diaspartos n. sp. Illustrations are provided for the identification of specimens and the presence of spatulate setae on first mesotarsomere is shown to be a unique characteristic of Scaponopselaphus within Xanthopygina.


Introduction
Between 1870 and 1940, the genus Trigonopselaphus Gemminger and Harold was treated as a dumping ground for species with securiform labial palpomere 3 and metallic coloration. Eventually species were moved out of Trigonopselaphus and into other genera such as Gastrisus Sharp, Nausicotus Sharp, and Torobus Herman (see Herman 2001 for the catalogue and Chatzimanolis 2013 for the morphogroups in Torobus), but great uncertainty still exists regarding the taxonomic boundaries of these genera. Recently, I have started dealing with the taxa originally placed in Trigonopselaphus: I erected the genus Terataki Chatzimanolis (Chatzimanolis 2013) to deal with several taxa that had been moved to Torobus and I revised the genus Trigonopselaphus (submitted) to establish the limits in that genus.
In this paper, I review the genus Scaponopselaphus Scheerpeltz. Scaponopselaphus was described (Scheerpeltz 1972) based on a single species and single specimen, Trigonopselaphus mutator Sharp, 1876. Sharp himself contemplated whether or not he should place the species in Trigonopselaphus (sensu Sharp 1876; currently this would be Torobus Herman) or erect a new genus for it, given that he thought that the absence of postcoxal process distinguished it from other species in Trigonopselaphus. Sharp (1876, p. 145) decided to place the species in Trigonopselaphus since " [ Trigonopselaphus] has already scarcely any definite meaning". Here, I reaffirm the generic status of Scaponopselaphus by providing novel morphological characters and I also describe a new species from Colombia.

Materials and methods
Photographs were taken using a Visionary Digital Passport System with a Canon EOS 40D camera and MP-E 65 lens. Images were automontaged using Helicon Focus 6.2.2. SEM photographs were taken using a Neoscope JEOL desktop SEM and processed using the Fluid Mask 3 software. All specimens were examined using an Olympus SZX10 stereomicroscope. Measurements were made using an ocular micrometer. Width: length ratio measurements were made on the widest and longest parts of the structure. The comparison between the length of the median lobe and the paramere excludes the bulbous basal part of the median lobe. Total body length is measured from the anterior margin of frons to the posterior margin of tergite VIII. Terminology and label data follow the procedure established by Ashe and Chatzimanolis 2003 and used in other Xanthopygina taxonomic works (e.g., Chatzimanolis 2004, Chatzimanolis 2008, Chatzimanolis 2012, Chatzimanolis 2013, Chatzimanolis 2014a, Chatzimanolis and Ashe 2009). The type locality of Scaponopselaphus mutator (Sharp) has been corrected as indicated in Asenjo et al. 2013 Antenna (Fig. 4b). Antennomeres 1-3 with multiple rows of macrosetae; antennomeres 4-11 with few macrosetae but covered with microtrichia; antennomeres 1-3 longer than wide; antennomere 4 quadrate; antennomeres 5-10 subquadrate to transverse, just slightly asymmetrical, becoming wider towards antennomere 10; antennomere 11 longer than wide.
Mouthparts. Labrum (Fig. 4a) medially incised. Mandibles as in Fig. 3a, b; curved, moderately elongate, with short tooth medially; left and right mandibles nearly symmetrical; with lateral fold extending from condyle to tooth; prostheca setose. Maxilla as in Fig. 3d; galea and lacinia densely setose; maxillary palpi 4-segmented; P small, about 1/3 as long as P ; P curved, elongate, subequal in length to P ; P -P with large setae apically; P elongate, slightly longer than P . Labium as in Fig Head and thorax of Scaponopselaphus Scheerpeltz. a: S. diaspartos Chatzimanolis b: S. mutator (Sharp) one long and one shorter anterolateral setae at each end. Labial palpi 3-segmented; with transverse microsculpture; P longer than P ; P trapezoidal; both P and P with several long setae; P securiform; P apex wide and with 4-5 rows of sensory setae.
Pronotum subquadrate (Fig. 2); hypomeron expanded ( Fig. 4c), with microsculpture; superior and inferior marginal lines of hypomeron separate throughout their lengths; superior line fully visible from above, extending around anterolateral margin of pronotum and contacting inferior line at neck fossa; no portion of dorsum of pronotum visible from below; without postcoxal process. Surface of pronotum shining, with scattered large setose punctures and microsculpture made of microlines (similar to but  Legs. Tarsal segmentation 5-5-5; pro-and mesofemur in both sexes with ctenidium ventrally and proximally; meso-and metatibia with multiple rows of spurs; protibia without multiple rows of spurs but with single row of spurs apically. Protarsus (Fig. 5d) enlarged in both sexes, with spatulate setae ventrally; mesotarsus ( Fig. 5e) not enlarged except tarsomere 1 in males twice as wide as other mesotarsomeres and with spatulate setae ventrally; metatarsus not enlarged. Empodium with two small setae.
Abdomen with paired protergal glands present; expanding from segment III to segment V (widest) and then becoming narrower towards segment VIII. Abdominal tergites III-V  (6) sternite VII in males with small porose structure (Fig. 5c). Male specimens in Scaponopselaphus can always be easily identified by the spatulate state on mesotarsomere 1, but some species in Phanolinopsis Scheerpeltz, Styngetus Sharp, Xenopygus Bernhauer may look superficially like Scaponopselaphus. However, these taxa do not have securiform labial P and their pronotum is not convex. Perhaps the most confusing scenario can be if someone has unsorted female specimens of Scaponopselaphus, Torobus and Zackfalinus Chatzimanolis; all these taxa have securiform labial P and somewhat similar head. However, Scaponopselaphus can be distinguished from these two genera based on the microsculpture of the head and the shape of the pronotum.

Distribution
Known from the state of Pará in Brazil, the department of Vaupés in Colombia, the province of Sucumbios in Ecuador, French Guiana, Guyana, the departments of Loreto and Madre de Dios in Peru and from Suriname (Fig. 8). Distribution map of S. diaspartos Chatzimanolis and S. mutator (Sharp).

Ecology
Specimens of Scaponopselaphus have been collected from wet tropical lowlands, however, further details on their habitat are unkown since almost all taxa have been collected with malaise or flight intercept traps. It is possible that the genus prefers forested habitats near rivers based on recent collecting events.
Head transverse, width: length ratio = 1.47; surface of epicranium flat; with mediumsized umbilicate punctures throughout surface except medially, distance between punctures varies but typically equals diameter of puncture. Eyes large, length of eyes / length of head = 0.58, distance between eyes as wide as 1.44 times length of eye.
Pronotum subquadrate, width: length ratio = 1.13; with scattered large umbilicate punctures, distance between punctures varies but typically equals 0.  Fig. 6; paramere divided to near base into two lobes; lobes narrower and subequal in length to median lobe; in dorsal view each lobe converging to rounded apex; in lateral view paramere slightly convex; with peg setae (sensory spinules) as shown in Fig. 6c, scattered throughout length of two lobes. Median lobe in dorsal view converging to narrow pointed apex; with single narrow dorsal tooth; in lateral view becoming much narrower near apex.

Diagnosis
Scaponopselaphus diaspartos can be distinguished from S. mutator based on the following characters: epicranium flatter and distance between eyes longer in S. diaspartos than in S. mutator; pronotum punctation more dense in S. diaspartos than in S. mutator (Fig. 2); and elytra punctation more sparse in S. diaspartos than in S. mutator (Fig. 1). Additionally, the following characters can be used to distinguish between males of the two species: in S. diaspartos posterior border of sternite VII with deeper median emargination than in S. mutator; in S. diaspartos peg setae are more scattered in the paramere (Fig. 6c) than the peg setae of S. mutator (Fig. 7c); and the median lobe of in S. diaspartos is as long as the paramere (Fig. 6a) while the median lobe in S. mutator is longer than the paramere (Fig. 7a).

Etymology
The specific epithet is derived from the modern Greek word διάσπαρτος (scattered) and refers to the distribution of the peg setae on the parameres. The epithet is a noun in apposition.

Description
Habitus as in Fig. 1b. Body length 10.1-10.5 mm. Coloration of head and pronotum metallic blue, green or blue-green (Fig. 2b); antennae and mouthparts orange, except antennomeres 4-11 covered with darker brown setae; elytra and abdomen light brown to brown, except intersegmental membranes yellow, sternite VIII and posterior 1/3 of sternite VIII orange; legs and pronotal hypomeron orange to brown.
Head transverse, width: length ratio = 1.38; surface of epicranium flat to slightly convex; with medium-sized umbilicate punctures throughout the surface except medially, distance between punctures varies but typically equals 1-2 times of puncture. Eyes large, length of eyes / length of head = 0.68, distance between eyes as wide as 1.28 times length of eye.  Fig. 7; parameres divided to base into two lobes; lobes narrower and shorter than median lobe; in dorsal view each lobe converging to rounded apex; in lateral view paramere slightly convex; with peg setae (sensory spinules) as shown in Fig. 7c, concentrated near apex of lobes. Median lobe in dorsal view converging to broad pointed apex; with wide bicuspid dorsal tooth; in lateral view becoming narrower near apex.

Diagnosis
See the Diagnosis of S. diaspartos.

Notes
These two specimens look rather similar to S. mutator, however, I am unable to place them in that species without male specimens from the same locality.

Discussion
In the recently completed molecular phylogeny of Xanthopygina, Scaponopselaphus was shown to be the sister group of Elmas Blackwelder (Chatzimanolis 2014b). Elmas is a rather distinctive genus of xanthopygine rove beetles with several unique morphological features (see Chatzimanolis 2003, Ashe andChatzimanolis 2006 for details) and at first glance, Elmas and Scaponopselaphus do not share many morphological characteristics. While a morphological phylogeny of Xanthopygina is still in preparation and a list of synapomorphies for the two genera is not currently available, there are certain common features worth mentioning here. First of all, the overall bauplan of the head for both genera is similar. Both genera have securiform labial palpus 3, which appears rather similar, and it is unlike the securiform palpus of Zackfalinus or Dysanellus Bernhauer (see Chatzimanolis 2012 for details on the morphology). Also, the secondary sexual structures on sternites VII-IX have the same kind of medial emarginations, although it is worth pointing out here that Elmas does not have a porose structure on sternite VII as in Scaponopselaphus.
Scaponopselaphus does not appear to be very common in collections around the world. During the last 15 years, I was able to locate the genus only in the four museum collections listed in the Materials and Methods sections as depositories, even though I have visited most major museums in North America and Europe. However, I doubt that the genus is rare in the field and it is more likely that we have not sampled adequately at the correct habitat. Based on recent collecting events, it appears that Scaponopselaphus is easily collected with flight intercept traps in localities near rivers and it is quite likely that many more new species are awaiting discovery in South America.