Haematochiton elateroides
| Haematochiton elateroides | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Clade: | Pancrustacea |
| Class: | Insecta |
| Order: | Coleoptera |
| Suborder: | Polyphaga |
| Infraorder: | Cucujiformia |
| Family: | Erotylidae |
| Genus: | Haematochiton |
| Species: | H. elateroides |
| Binomial name | |
| Haematochiton elateroides Gorham, 1888 | |
| Synonyms | |
|
Haematochiton bisculptum Casey, 1916 | |
Haematochiton elateroides is a small black-and-red species of pleasing fungus beetle (family Erotylidae) from Central and North America. Among its family, the genus Haematochiton is placed in subfamily Tritominae, or – in taxonomic arrangements that prefer a more comprehensive subfamily Erotylinae – in tribe Tritomini of the Erotylinae.[1][2]
Whether the small and little-studied genus Haematochiton is distinct from its close relative, the hugely successful Mycotretus radiation, remains to be determined.[3]
Description
[edit source]Haematochiton elateroides are small beetles, around one-fifth of an inch long and slightly less than half as wide (4.7-6.2 mm long and 2.2-2.9 mm wide) as adults. They are blackish overall except for the elytra, which are blood-red with black tips. The body is elliptical, with a smoothly rounded head and an equally blunt wingtip; apart from tiny pin-prick-like punctures, the carapace surface is smooth and shiny. On the sides of the pronotum and in lengthwise rows on the otherwise smooth elytra, these punctures are rather large, conspicuously elongated, and flat-bottomed; such punctuation is highly unusual among Erotylidae and – when observed with a magnifying glass – usually sufficient to identify this species.[3]
Head
The head lacks file-like structures for stridulation, and has no constriction between the rather small compound eyes. The individual ommatidia are also small; this species is probably diurnal or crepuscular, but generally does not seem to rely on eyesight much. The punctures are sparse but fairly large and flat-bottomed at the base of the head, becoming smaller and denser towards the top. The epistome is unmargined, due to the ocular striae not reaching beyond the antenna insertion points, and ends in an almost straight edge with a slight concave indentation. The antenna length is about two-thirds of the pronotal base width, with antenna segment 3 almost as long as the segments 4 and 5 together, and a large "club" forming the antenna tip.[3]
The maxillary palps are curved, with a basal segment that is as long as segments 2 and 3 together, and an end segment that is rounded, barely half as long as it is wide, and lacks a brush; the maxillary lacinia have two incurved teeth at the tip. The labium has a moderately-sized and roughly square-shaped mentum with a three-pointed tip, and palps which end in a comparatively small hatchet-shaped segment with a strong bristle at the outer side and a sharply cut-off tip which bears a tiny brush. The postmandibular lobes are little developed and effectively invisible.[3]
Body, wings and legs
The prothorax is almost as wide at the base as the wings at their widest point. The pronotum is a blunt trapezoid, with the forward edge slightly shorter than the rear edge and slightly longer than the pronotum's lengthwise dimension; the sides curve towards the forward end, and the central area slopes to a slight hump between the midpoint and the forward edge. A thin margin runs around the pronotum except on the forward edge between the compound eyes (unlike in Mycotretus – see below – where the pronotal margin is continuous all around). There are no conspicuous pores in the corners of the pronotum, but it is strewn with small and shallow punctures in the central area, with the lateral third at each side having strikingly different elongated larger and flat-bottomed punctures. The tip of the prosternum is not compressed, and vertically evenly rounded; the lengthwise lines at the center margin of the leg attachments run almost parallel, with a slight widening to the rear.[3]
On the meso- and metasternum, the lines between the leg attachments are at most a short basal trace, but usually entirely absent. The scutellum may be smooth or densely strewn with pronounced punctures; this varies individually or perhaps according to age. The elytra have a distinct margin at the base, which does not extend all the way to the tip; they are ornamented with regular lines of large, lengthwise elongated, and flat-bottomed punctuations, and smooth in between these.[3]
The attachments of each leg pair are neither particularly close or conspicuously far away. The legs' femora have a barely notable compression, are not much thickened, and bear a keel on their posterior edges. The tibiae are slender, slightly curved and a bit widened towards the ends. Segment 4 of the tarsi is reduced, and attached to the upper centerside of segment 3.[3]
Males, but not females, have a conspicuous roughly punctated spot in the center of the underside of the first abdominal segment. The aedeagus of the male genitalia strikingly resembles that of Mycotretus nigromanicatus, in having a distinctive anterior end of the internal sac. The median lobe has a narrow membrane along the widely gaping opening of the median orifice. On the other hand, the female genitalia resemble various other Erotylidae in their details: The genital tube is overall shaped as in Ischyrus quadripunctatus, however the seminal receptacle lacks the conspicuously large extension seen in that species. There is one very long bristle in the middle of each stylus as in Aporotritoma pulchra. Tergite 8 is half again as wide as it is long, and resembles that of Triplax thoracica, with strongly sclerotized lines along the sides, and in the centerline near the tip a deep but narrow membranous indentation.[3]
Distribution and ecology
[edit source]
This beetle occurs in montane pine forests of northern Mexico and the adjacent USA, where it has been reported from altitudes of 8000-9000 feet (2500-3000 m) AMSL. It was described by Henry S. Gorham in 1888 based on specimens from Pueblo Nuevo, Durango,[4] in the Sierra Madre Occidental north of the Mexican Plateau. US records are from Arizona, mostly from localities in the Chiricahua Mountains near the Mexican border such as Pine Creek and Rustler Park, but also from Phoenix further to the northwest. Apparently, this species is restricted to the Sierra Madre Occidental pine–oak forests ecoregion and to patches of similar habitat on the moisture-catching mountains that rise at the boundary of the Chihuahuan and Sonoran Deserts, where they seem to be most abundant (but still quite scarce, or maybe hard to find) around July. Beyond that, however, its ecology remains elusive; as late as the mid-20th century, nothing at all was known about this beetle's habits.[3]
The Arizonan population was at first described by Thomas L. Casey Jr. as a distinct species H.bisculptum, but the supposedly distinguishing traits were based on a hypercorrect reading of Gorham's description of H.elateroides. Comparison of Arizonan and Mexican specimens shows only some individual variation, with no consistent differences between the local populations.[3]
References
[edit source]- ↑ Alvarenga, Moacyr (1994): Catálogo dos Erotylidae (Coleoptera) Neotropicais. [Catalogue of Neotropical Erotylidae (Coleoptera). Portuguese with English abstract.] Revista Brasileira de Zoologia 11(1): 1-175. doi:10.1590/S0101-81751994000100001.
- ↑ "Haematochiton elateroides". iNaturalist. Retrieved 2026-07-09.
- 1 2 3 4 5 6 7 8 9 10 Boyle, Wilford Wayne (1956): A revision of the Erotylidae of America north of Mexico (Coleoptera). Bull. AMNH 110: 61-172. PDF fulltext
- ↑ Gorham's toponym "Ciudad in Durango" can also refer to the Ciudad ("city center") neighborhood of the state capital Durango, which is, however, at an altitude of some 6000 ft. The "8100 feet" above sea level given by Gorham for the collection locality of the H.elateroides holotype precisely matches the elevation of the village of Pueblo Nuevo, locally known as La Ciudad ("the city") at Gorham's time.
