Derolathrus foveiceps, Théry, 2023

Théry, Thomas, 2023, Description of Derolathrus foveiceps n. sp. from Florida (Coleoptera: Jacobsoniidae), Faunitaxys 11 (36), pp. 1-4 : 1-2

Derolathrus foveiceps n. sp.

( Fig. 1 -3 )

ZooBank: http://zoobank.org/ F96750B1-2482-4FC5-BF9A-BE04968E29DF

Holotype, ♀, glued on a point; the head glued beside the body, with both left anterior and median legs, and both right anterior leg and median tarsus partially missing: FLA: DadeCo. / Everglades N, Royal Palm / Hammock, 2.v-2.viii.85 / S&J Peck, hammock for. / malaise-FIT (rectangular white label) // Derolathrus /new species,/withdepressionatback of head, / like specimens in BMNH / from Costa Rica; det, S. Peck 2009 // HOLOTYPE / Derolathrus foveiceps n. sp. / T. Théry des. 2023 (rectangular red label) [CMN] .

Diagnosis. – Derolathrus foveiceps n. sp. can be separated from other Derolathrus species by the combination of the following characters: winged species; eyes developed and large; dorsal surface of head and of the anterior 4/5 of pronotum with a netting of triangular to rounded polygons, with two types of punctation: type 1 corresponds to rounded and shallow depressions, each depression bearing a seta inserted at a small puncture; type 2 corresponds to a simple puncture located at the intersection of 4-5 polygons; head with punctures not aligned in rows, but with an elongated large and deep median vertexal depression; pronotum with rounded sides on its anterior 4/5, its base suddenly constricted posteriorly with its 1/5 posterior surface covered with a netting of strongly concave more or less squared depressions, lacking dorsolateral ridges, with a deep elongated median depression; each elytron with an entire sutural stria, arched at base in a strongly reduced second stria, striae deeper and more impressed at base but with no shallow pit; metaventrite very long, about 3.5 times longer than the first visible abdominal ventrite; median and hind legs slender.

Description

– Total lengthabout 0.98mm. – Winged species, with developedand large eyes. – Body shape subcylindrical, narrowly elongate. – Color yellowishbrown, integument slightly shiny ( Fig. 1-3 ).

Head. – More or less squared, slightly wider than long (HL: ~ 165 µm; HW:~ 203 µm), widest at eyes, constricted at temples. – Temples short, less than 1/3 diameter of eyes; eyes rounded, large, protruding, slightly longer than distance between their anterior margin and antennal insertion, with about 25 -30 ommatidia each. – Vertex flattened with a quite elongated, large and deep median depression. – Frons slightlyconvex betweenantennaltubercles. – Antennal tubercles protruding; dorsal surface lacking rows of punctures. – Integumental sculpturing composed of a polygonal netting, the polygons triangular to rounded, with two kinds of punctation: the first corresponds to some rounded and shallow depressions, especially laterally, each depression bearing a seta inserted in a small puncture, and the second corresponds to a simple puncture locatedat the intersectionof 4- 5 polygons ( Fig.1 - 3 ); netting more impressed laterally towards eyes, less impressed anteriorly to frons, around and posteriorly to the vertexal depression. – Setation composed of suberect to recumbent setae inserted in the punctures of the rounded depressions, when visible, in simple punctures anteriorly when the depressions disappear; some setae present on eyes, inserted between ommatidia. – Antennae with 11 antennomeres; the first one partially hidden by the lateral margin of head; antennomeres 3- 9 moniliform; antennomeres 10 -11 short, fused, forming a club, antennomere 11 slightly longer than antennomere 10 ( Fig. 2 ).

Pronotum. – Almost as long as wide (PL: ~ 222 µm; EW: ~ 219 µm), widest at anterior 1/4, subquadrate on its 4/5 anterior length with its sides slightly curved, its base suddenly constricted posteriorly at its 1/5 posterior; with a deep and elongated median depression. – Integumental surface of the 4/5 anterior with the same integumental surface than the head, setiferous depressions more or less aligned in at least 4 rows at each side of the median depression, surface of its 1/5 posterior covered with a netting of strongly concave more or less squared depressions ( Fig. 3 ).

Metaventrite. – Very long, more than 3.5 times longer thanthe first visible abdominal ventrite and about slightly longer than all abdominal ventrites combined.

Abdomen. – Five visible abdominal ventrites, the first one the longest.

Elytra. –About 2 times longer than wide (EL: ~ 596 µm; EW: ~ 285 µm), widest at midpoint; apices rounded-truncate, covering entirely the abdomen. – Sutural stria entire butnot reachingapex,mainlyparallel tosuture but slightly diverging from it posteriorly, deeper and more impressed at base and ending in an arc forming a strongly reduced second elytral stria but without any basal pit; no further elytral stria but a small and barely visible basal notch. – Integumental sculpturing composed of a netting of more elongated polygons than those of pronotum. – Setae erect, more or less aligned in several rows; no punctures except minute ones at setal insertions.– Scutellum not visible ( Fig. 1 ).

Legs. – Femora and tibiae slender; tibiae constricted anteriorly.

Genitalia. – Not studied.

Differential diagnosis. – By the kind of its dorsal integumental structure, Derolathrus foveiceps n. sp. can be placed in the same group as D.parvulus (Rücker) , D. cavernicolus Peckand D.troglophilus (Sen Gupta) ,all exhibiting shallow setiferous depressions on the head and on the pronotum. More particularly, D. foveiceps n. sp. is very close to D. troglophilus , by the size and the shape of those depressions. However, D.foveiceps n. sp. can be easily separated from all these species by its second elytral stria strongly reduced to a basal arc, by the absence of an elytral basal pit and especially by its large median vertexal depression ( D. parvulus , D. cavernicolus and D. troglophilus show a strong and deep basal fovea, a longer second elytral stria and do not possess any vertexal depression).

Etymology. – The specific name is related with the deep and longitudinal median depression of the head.

Distribution. – Derolathrus foveiceps n. sp. is currently only known from the Everglades National Park, Florida, USA.

Discussion

The minute size and the high fragility of this unique specimen of D. foveiceps n. sp. did not permit to study all of its characters, notably those of the ventral part. However, its dorsal integumental structures, the shape of both the elytral stria and the discal pronotal depression, the absence of a basal elytral pit and above all the presence of a clear vertexal depression, support the conclusion that this specimen belongs to a different species from those already described.The presence of a vertexal depression is also mentioned by Peck (2010) for other material from Costa Rica. However, according to this author, those specimens exhibit a different pronotal integumental structure and would belong to another species. Because of the tiny size and scarcity of Derolathrus specimens, it islikely thatthe diversity of thatgroupis underestimated, and that numerous species remain to be discovered and described. Notably,several unidentified specimens collected from areas where no described Derolathrus species are yet recorded (Africa, Central and South America (including Galapagos Is.), Australia, New Zealand, Solomon Is. ( Peck, 2010; Lawrence & Leschen, 2010; Cai et al., 2015; Théry, 2023) are held in several institutions and are waiting for to be studied.

Figures

Figures 1-3. Derolathrus foveiceps n. sp., holotype, dorsal view (Scale: 100 µm). 1. Elytra and pronotum. 2. Head. 3. Pronotum (with detail of punctation).