Dactylosternum, WOLLASTON, 1854

Angus, Robert B, Sadílek, David, Shaarawi, Fatma, Dollimore, Hayley, Liu, Hsing-Che, Seidel, Matthias, Sýkora, Vít & Fikáček, Martin, 2021, Karyotypes of water scavenger beetles (Coleoptera: Hydrophilidae): new data and review of published records, Zoological Journal of the Linnean Society 192 (3), pp. 958-958 : 958-

GENUS DACTYLOSTERNUM WOLLASTON, 1854

( FIG. 15D–G, I )

Material examined: Dactylosternum corbetti (Balfour- Browne, 1942): 1 male ( NMPC): Taiwan, Nantou County, 4.8 km SSE of Tonglin, Beikeng Creek Trail , 24.04791°N 120.78434°E, 3.x.2018, M. Fikáček, F.-S. Hu, W.- R. Liang & H.-C. Liu lgt .

Dactylosternum flavicorne (Mulsant, 1844) : 1 male, 1 female ( BMNH): Dominican Republic, lowland rainforest, locality unknown, R. Angus lgt .

Karyotype: 2 n = 26 + Xy (♂). In Dactylosternum flavicorne ( Fig. 15D – F ), the autosomes are metacentric to submetacentric, with the smallest pair about half of the length of the largest pair. The X chromosome is metacentric and the largest in the karyotype. All the chromosomes, except the dot-like Y, have large centromeric C-bands. The karyotype of Dactylosternum corbetti ( Fig. 15G ) has the autosomes and X chromosome metacentric to submetacentric and with smaller C-bands than in Dactylosternum flavicorne . Pair 1 is distinctly longer than the others, and the X chromosome is about as long as pair 5.

TRIBE PROTOSTERNINI

Figures

Figure 1. Tissuesof hydrophiloid beetles used for chromosome preparations (as dissected, without any additionaltreatment, (B–E) in dorsal view; (A) Helophorus grandis; (B, C, I) Laccobius bipunctatus; (D–H) Coelostoma orbiculare). A, egg with a developing embryo. B–C, internal organs of the same male specimen in translucent light (B) and on black background (C). D, internal organs of a female with digestive system pulled aside. E, internal organs of male specimen. F, details of ovarioles and associated accessory glands. G–I, detail of midgut structure on black background (G) and in translucent light (H, I). Abbreviations: accg, accessory glands; aed, aedeagus; hg, hindgut; mg, midgut; Mt, Malpighian tubes; oo, ovarioles; ovi, ovipositor; rc, regeneration crypts; tes, testes. Not to scale.

Figure 2. Karyotypes of the Amphiopini and Laccobiini. A–E, Amphiops mater, mitotic methaphase from midgut. F–L, Laccobius decorus, mitotic metaphase from midgut.A, C, F, H, J, without treatment. B, D, G, I, K, C-banded. Habitus figures: (E) Amphiops mater; (L) Laccobius decorus.

Figure 3. Karyotypes of the Laccobiini, without treatment. A–H, Paracymus: (A–B) Paracymus aeneus, mitotic metaphase from midgut; (C–D) Paracymus scutellaris (C, spermatogonial mitosis, metaphase; D, mitotic metaphase from midgut.); (E–G) meiotic metaphase I from testes (E, Paracymus aeneus; F–G, Paracymus scutellaris). I–M, Tormus, mitotic metaphase from midgut: (I, K) Tormus posticalis; (J, L) Tormus helmsi. Habitus figures: (G) Paracymus scutellaris; (M) Tormus helmsi, from Fikáček et al. (2013).

Figure 4. Mitotic karyotypes of Hydrobius. A–C, Hydrobius fuscipes, testes. D, Hydrobius arcticus, midgut. E, Hydrobius rottenbergii, testes.F–H, Hydrobius subrotundus (F, midgut; G–H, testes). I, Hydrobius pui, testes.A, D–I, without treatment. B, C, C-banded. J, habitus of Hydrobius fuscipes.

Figure 5. Karyotypes of the Hydrobiusini. A–D, Limnohydrobius convexus: (A–B) mitosis, midgut; (C–D): testis, prometaphase. F–J, Limnoxenus niger: (F–H) midgut; (I–J) meiotic metaphase I, testes. A–C, E–F, I, without treatment. D, G, H, J, C-banded. Habitus figures: (E) Limnohydrobius convexus; (K) Limnoxenus niger.

Figure15. KaryotypesoftheCoelostomatiniand Protosternini.A–C,Coelostomaorbiculare,embryo(A,with B-chromosomes; B–C, without B-chromosomes). D–F, Dactylosternum flavicorne, embryo. G, Dactylosternum corbetti, mitosis, midgut. J–K, Protosternum abnormale, meiotic nuclei from testes. A–F, J, K, without treatment. G, C-banded. Habitus figures: (H) Coelostoma orbiculare; (I) Dactylosternum corbetti; (L) Protosternum abnormale, from Fikáček et al. (2018).