Dactylosternum Wollaston, 1854

Mai, Zuqi, Hu, Jian, Minoshima, Yûsuke N., Jia, Fenglong & Fikáček, Martin, 2022, Review of Dactylosternum Wollaston, 1854 from China and Japan (Coleoptera, Hydrophilidae, Sphaeridiinae), Zootaxa 5091 (2), pp. 269-300 : 271-272

publication ID	https://doi.org/ 10.11646/zootaxa.5091.2.3
publication LSID	lsid:zoobank.org:pub:C8081B60-C872-4A19-9291-22A42DC8B763
DOI	https://doi.org/10.5281/zenodo.5847173
persistent identifier	https://treatment.plazi.org/id/03F687FE-434C-BC62-0CD7-FDDCFA1472A8
treatment provided by	Plazi
scientific name	Dactylosternum Wollaston, 1854
status

Treatment

Dactylosternum Wollaston, 1854 View in CoL

( Figs. 1–71 View FIGURES 1–4 View FIGURES 5–10 View FIGURES 11–16 View FIGURES 17-19 View FIGURES 20–24 View FIGURES 25–29 View FIGURES 30–32 View FIGURES 33–38 View FIGURES 39–47 View FIGURES 48–63 View FIGURES 64–69 View FIGURES 70–71 )

Dactylosternum Wollaston, 1854: 99 View in CoL . Type species: Dactylosternum roussetii Wollaston View in CoL

For complete synonymy, see Hansen (1999).

Diagnosis. Body oblong oval to broadly oval, moderately to strongly convex, more or less uniformly brown to black; antenna with 9 antennomeres in Asian species, antennal bases concealed by lateral parts of clypeus, club (antennomeres 7–9) loosely segmented or compact; labrum completely concealed by clypeus or partially exposed in front of clypeus in Chinese and Japanese species; frontoclypeal suture distinct; maxillary palps with 4 palpomeres, stout; labial palps with 3 palpomeres, rather stout; gula forming a transverse triangle posteriorly, narrow and parallelsided anteriorly; prosternum more or less tectiform medially, often with a distinct tooth anteromedially; hypomeron pubescent except on marginal portion, without defined antennal grooves; metaventrite with pubescence except on raised median portion; metaventral process strongly projecting anteriorly between mesocoxae, abutting mesoventral elevation; elytron with at least 9 rows of serial punctures or striae, the outer serial punctures usually larger and deeper than the inner serial punctures; sides of elytron more or less explanate at least in posterior half; elytral epipleuron wide and reaching elytron end; first abdominal ventrite with complete or almost complete carina medially.

Biology. All species of Dactylosternum for which biology is known are terrestrial. They usually occur in various types of decaying plant material, including that under bark of freshly cut trees ( Bloom 2014) and in tropical forest leaf litter ( Fikáček 2010, Fikáček et al. 2020). In tropical areas, Dactylosternum abdominale ( Fabricius, 1792) was found in banana trees ( Figs. 65, 67 View FIGURES 64–69 ) and its larvae are predators of the banana weevil ( Koppenhöfer 1995); in temperate areas the same species is found in domestic waste or farmyard manure ( Lõkkös 2009). Dactylosternum cacti (LeConte, 1855) in inhabiting rotting cactus tissues ( Archangelsky 1994, Arriaga-Varela et al. 2019). Many Chinese species were collected in the decaying pseudostem of banana plants and in rotten wood ( Figs. 67–69 View FIGURES 64–69 ). Dactylosternum nanlingensis Mai et Jia , sp. nov. was collected from fungal hyphae on fallen wood ( Figs. 64, 66 View FIGURES 64–69 ), and D. songxiaobini Mai et Jia , sp. nov. was collected from a rotten wood with termites.

A list of Chinese Dactylosternum Wollaston, 1854

Dactylosternum abdominale ( Fabricius, 1792)

Dactylosternum corbetti Balfour-Browne, 1942

Dactylosternum frater Mai et Jia , sp. nov.

Dactylosternum hydrophiloides (MacLeay, 1825)

Dactylosternum latum ( Sharp, 1873)

Dactylosternum nanlingensis Mai et Jia , sp. nov.

Dactylosternum pseudolatum Mai et Jia , sp. nov.

Dactylosternum pui Jia, 2002

Dactylosternum salvazai Orchymont, 1925

Dactylosternum songxiaobini Mai et Jia , sp. nov.

A list of Japanese Dactylosternum Wollaston, 1854

Dactylosternum abdominale ( Fabricius, 1792)

? Dactylosternum latum ( Sharp, 1873) (doubtful)

A key to species of Dactylosternum in China and Japan

1 Antennal club loosely segmented ( Fig. 39 View FIGURES 39–47 ). Body broadly oval, strongly convex................................... 2

- Antennal club compact ( Fig. 40 View FIGURES 39–47 ). Body elongate to oval, anterior half of elytra nearly parallel-sided, weakly to moderately convex.............................................................................................. 4

2(1) Anterior margin of clypeus pubescent; elytral series 1–3 reaching basal half of elytra; punctures on pronotum simple, without lateral scars ( Fig. 43 View FIGURES 39–47 ); ventral surface of mesofemora fully covered with dense pubescence except on extreme apex ( Fig. 41 View FIGURES 39–47 ); body reddish brown to piceous brown ( Fig. 4 View FIGURES 1–4 ). China.................................................. D. pui Jia View in CoL

- Anterior margin of clypeus not pubescent; all elytral series nearly reaching elytral base; punctures of pronotum with lateral scars ( Figs. 44–45 View FIGURES 39–47 ); ventral surface of mesofemora only covered with pubescence along anterior margin ( Fig. 42 View FIGURES 39–47 ); body dark brown to black....................................................................................... 3

3(2) Body size less than 4 mm; elytral sutural stria distinct in posterior half; with nearly 20 serial punctures. China. … D. songxiaobini View in CoL ......................................................................... Mai et Jia, sp. nov.

- Body size more than 4 mm; elytral sutural stria almost reaching basal third elytra; with 10 serial punctures. China................................................................................ D. nanlingensis Mai et Jia View in CoL , sp. nov.

4(1) Body size less than 5 mm; pronotum with distinct microsculpture on interstices or arising from the punctures, at least on the lateral portion ( Figs. 46–47 View FIGURES 39–47 )............................................................................. 5

- Body size more than 5 mm; pronotum without any trace of microsculpture on interstices............................. 6

5(4) Body size less 4 mm; moderately convex; each puncture on vertex, pronotum, scutellum and elytron connected with two diverging impressed short lines ( Fig. 46 View FIGURES 39–47 ). China....................................... D. corbetti Balfour-Browne View in CoL

- Body size over 4 mm; weakly convex; clypeus, posterior margin of vertex and lateral portion of pronotum with distinct meshlike microsculpture on interstices, the lines are not connected to punctures ( Fig. 47 View FIGURES 39–47 ). China and Japan................................................................................................. D. abdominale (Fabricius) View in CoL

6(7) Body weakly convex; anterior margin of clypeus with distinct marginal rim ( Fig. 18 View FIGURES 17-19 ); interstices of elytral intervals with dense micropunctures, especially in posterior half ( Fig. 51 View FIGURES 48–63 ); median lobe very short and broad, apex rounded, reaching only to the midlength of parameres; parameres almost as long as phallobase ( Fig. 24 View FIGURES 20–24 ). China........... D. hydrophiloides (MacLeay) View in CoL

- Body moderately convex; anterior margin of clypeus without marginal rim ( Fig. 19 View FIGURES 17-19 ); elytral interval punctures with associated microsculpture especially in posterior half, but intersticed smooth ( Figs. 52–55 View FIGURES 48–63 ); median lobe a little shorter than parameres, pointed at apex; parameres distinctly longer than phallobase................................................... 7

7(6) Posterior margin of abdominal ventrite 5 with a distinct marginal rim and a stria ( Figs. 60–61 View FIGURES 48–63 )........................ 8

- Posterior margin of abdominal ventrite 5 with very fine marginal rim or without it, without stria ( Figs. 62–63 View FIGURES 48–63 )........... 9

8(7) Anteromedial portion of metaventrite behind metaventral process with a Λ-shaped divergent ridges ( Fig. 57 View FIGURES 48–63 ); each elytral ground puncture attached with a K/H-shape microsculpture especially in the posterior half ( Fig. 53 View FIGURES 48–63 ); posteromedial portion of abdominal ventrite 5 with mesh-like microsculpture ( Fig. 61 View FIGURES 48–63 ); outer margin of parameres not sinuate, not so curved as in D. pseudolatum View in CoL ( Figs. 25a, 25b View FIGURES 25–29 ); ventral plate of the median lobe rounded apically ( Fig. 25c View FIGURES 25–29 ). China... D. salvazai Orchymont View in CoL

- Anteromedial portion of metaventral process with a short transverse groove ( Fig. 56 View FIGURES 48–63 ); each elytral ground puncture attached with one/two transverse lines especially in posterior half ( Fig. 52 View FIGURES 48–63 ); posteromedial portion of abdominal ventrite 5 with fine punctures ( Fig. 60 View FIGURES 48–63 ); parameres distinctly sinuate on outer margin and more curved subapically ( Figs. 27–29 View FIGURES 25–29 ); ventral plate of the median lobe strongly pointed apically ( Figs. 27c, 28c View FIGURES 25–29 ). China................... D. pseudolatum Mai et Jia View in CoL , sp. nov.

9(7) Anteromedial portion of metaventral process with a strongly impressed pit ( Fig. 58 View FIGURES 48–63 ); median lobe widest at basal third or at midlength, outer margin nearly parallel-sided medially, gonopore situated subapically ( Figs. 30–38 View FIGURES 30–32 View FIGURES 33–38 ). China and possibly Japan.................................................................................. D. latum (Sharp) View in CoL

- Anteromedial portion of metaventral process slightly depressed ( Fig. 59 View FIGURES 48–63 ); median lobe widest at basal third, gradually narrowing towards apex, outer margin not parallel-sided, gonopore situated apically ( Fig. 26 View FIGURES 25–29 ). China...... D. frater Mai et Jia View in CoL , sp. nov.