Xystosomus elaphrinus Bates 1863
Creators: name: Erwin, Terry L.
Publisher: name: Zenodo
Year: 1973
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Xystosomus
Xystosomus elaphrinus

description: <i>Xystosomus elephrinus</i> Bates, 1871b:267. [<i>Lectotype</i>, male, in MHNP, here selected. Type-locality: Ega (Teffe), Brazil.] DESCRIPTION.—Form: Similar to members of the holarctic genus <i>Elaphrus,</i> with broad elytra, narrow pronotum, and huge eyes. <i>Color:</i> Head and body piceous; pronotum and elytra with metallic green luster; appendages testaceous or piceous or bicolored. Head: Broad between eyes; frontal furrows well impressed and separated from eye by a linear costa; eyes huge and hemispherical. Pronotum (Figures 1, 37): Quadrate (W/ <b>L, x</b> 1.45; range, 1.35-1.53; 29 specimens); lateral setigerous pores present just anterior to middle and at hind angles; laterobasal carina well developed; hind angles sharp, acute, sides anterior to angles sinuate; side margins broadly explanate to lateral setigerous pores, narrowly explanate anterior to pores. <i>Elytra:</i> Each elytron with eight rows of serial discal intervals flat, intervals between coarse <b>basal</b> punctures uneven and partially convex; side <b>margins</b> broadly explanate; humeral projection well developed, obtuse; chaetotaxy as in <i>X</i>. gruti; plica short, evident externally. <i>Microsculpture:</i> As in <i>X</i>. <i>gruti</i> <i>,</i> except more finely impressed or nearly effaced in part; head shiny and without meshes. <i>Secondary</i> sexual characters: Male genitalia characteristic of gruti <i>group</i> members in internal sac; median lobe larger, more twisted, and with bent apex (Figure 40). Female genitalia as in <i>X</i>. gruti, except stylus (Figure 42) blunt at apex, <b>exceeded</b> in length by lateral spines. <i>Size:</i> Twenty-nine specimens: length, 3.7-4.3 mm; width, 1.6-1.9 mm. VARIATION.—The specimens I have seen <i>can</i> be divided into two groups on the basis of elytral punctation and leg color. One morph (all <i>specimens</i> south of the Amazon Basin or in the southern part of it) has each elytron with eight entire rows of numerous small serial punctulae with small, noncoarse punctures basally in rows 4—6. This morph has testaceous legs. The other morph (all specimens from French Guiana north) has each elytron with eight abbreviated rows of either small punctulae (rows 1 and 2) or large, coarse, well-impressed punctures (rows 3-8) with only rows 7 and 8 entire; rows 1-6 effaced in apical half. This morph has <i>piceous</i> or darkly infuscated legs. Unfortunately, all "pale-legged morph" specimens are females. Further material, especially males, may clarify the situation and indicate whether the southern form is conspecific (or <i>perhaps</i> subspecific). The type-specimen is from an intermediate area, but it agrees in all respects to the northern "dark-legged morph." NATURAL HISTORY.— <i>Adults</i> were collected January to March, in <i>May</i>, July to September, and in November. One teneral specimen was collected in July. Nevermann recorded four specimens from "under loose bark, January, July, September, November"; one specimen "on tree fungus, February"; one specimen "off pieces of bark, May"; and one specimen "at light, May." DISTRIBUTION (Figure 70).—The range of this species extends from Costa <b>Rica</b> to the Amazon Basin in lowland tropical forests. LOCALITY <i>RECORDS</i> (Figure 70).—I have <b>seen</b> 30 specimens from the following localities: <b>CENTRAL</b> <i>AMERICA</i>: COSTA <b>RICA:</b> Hamburg Farm at Reventazon <b>(</b> USNM <b>);</b> Lasmercedes <b>(</b> USNM <b>).</b> PANAMA: <b>Bugaba (</b> MHNP <b>);</b> Cabima <b>(</b> USNM <b>);</b> Matachin <b>(</b> MHNP <b>).</b> SOUTH <b>AMERICA:</b> BRAZIL: Amazonas Province: Teffe <b>(MHNP).</b> Goyaz Province: Jatahy <b>(</b> MHNP <b>),</b> Rio Verde <b>(MHNP).</b> Pari Province: Baragance <b>(</b> MHNP <b>).</b> BRITISH <i>GUIANA</i>: Bartica <b>(</b> MHNP <b>);</b> Kartabo Point <b>(</b> MCZ <b>).</b> COLOM- BIA: San Carlos <b>(</b> MHNP <b>).</b> FRENCH <i>GUIANA</i>: Cayenne <b>(</b> MHNP <b>);</b> Roches de Kourou <b>(MHNP).</b>
description: Published as part of <i>Erwin, Terry L., 1973, Studies of the subtribe Tachyina (Coleoptera: Carabidae: Bembidiini), Part I: A revision of the Neotropical genus Xystosomus Schaum, pp. 1-39 in Smithsonian Contributions to Zoology 140</i> on pages 21-22, DOI: 10.5479/si.00810282.140, http://zenodo.org/record/3828531