Xenobates Esaki, 1927
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publication ID |
https://doi.org/ 10.37520/aemnp.2021.012 |
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publication LSID |
lsid:zoobank.org:pub:71F65F83-C39D-470A-9483-107C527E4FD9 |
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persistent identifier |
https://treatment.plazi.org/id/039CFA2B-FFC1-FFA5-FEBE-F96929E6FAB1 |
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treatment provided by |
Carolina |
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scientific name |
Xenobates Esaki, 1927 |
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Xenobates Esaki, 1927 View in CoL
Type species. Microbates seminulum Esaki, 1926 (original designation).
Diagnosis (modified from Aඇൽൾඋඌൾඇ 2000). Small Veliidae (BL 1.2–2.9 mm; males smaller than females), of robust, ovate built; in some species the female’s abdomen posteriorly more convergent, almost pointed. Only apterous morph known. Head and pronotum of almost all species with yellow, orange, or pale brown markings ( Figs 1–8 View Figs 1–4 View Figs 5–8 ). Eyes of moderate size, larger than in Halovelia and Haloveloides , interocular width as long as half of head width or only slightly longer. Antenna ( Figs 9–12 View Figs 9–26. 9–12 ) slender, length about half to three fourths of body length; in most species antennomere 1 longer than 3. Pronotum very short ( Figs 1–8 View Figs 1–4 View Figs 5–8 ). Foreleg of male without modification on protrochanter and lacking a grasping comb on protibia. Middle legs relatively short when compared to Halovelia and Haloveloides ; extensor face of mesofemur ( Figs 13–16 View Figs 9–26. 9–12 ), mesotibia, and mesotarsus with rows of setae, that are often long, but in some species short and inconspicuous; mesotarsus length less than 0.4 times mesotibia length; mesotarsomere 1 longer than 2. Metafemur of male ( Figs 17, 19 View Figs 9–26. 9–12 ) at most slightly thickened (near base, not in middle). Metatarsomere 1 much longer than 2. Abdomen relatively short and tapering in width posteriorly in both sexes. Segment 8 with genitalia clearly protruded from segment 7. Parameres ( Figs 21, 22 View Figs 9–26. 9–12 ) long, symmetrical, and falciform. Comparative notes. In the field, Xenobates can usually be identified easily, because Xenobates inhabits mangroves and Nypa swamps, habitats where the related genera cannot be found regularly. Morphologically, Xenobates is characterized by extended areas bearing silvery hair patches, a relatively short middle leg (compared to Halovelia and Haloveloides ), and relatively large eyes (compared to Halovelia ). Males do not possess a protibial grasping comb (in contrast to Halovelia ). Many species of Xenobates possess a row of long setae on the extensor side of the mesofemur, which is unknown from other haloveliine genera.
Taxonomically important characteristics. Species of Xenobates show only little intraspecific variability, which makes identification relatively safe. On the other hand, there are not many differentiating characters between species. Colouration is relatively stable in species, the orange to yellow patches vary little in their extension. An exception is X. nypicola sp. nov., a relatively light-coloured species, where the shadings of brown considerably vary between specimens. Pilosity and setiferation offer important characters for species discrimination. The species have differently extended silvery patches on their dorsum. The arrangement of setae on the legs, and the length of setae on the extensor side of mesofemora are further important characters. Xenobates nypicola sp. nov. can be immediately identified by the numerous setae on its antennae. Females often possess characteristic setae on the posterior segments of the abdomen. Morphometry is an important tool for identification as well. The relative length of antennae, of individual leg segments, eye size etc. help to distinguish species. Males have secondary sexual characters on their abdominal sternites (humps, grooves, carinae) that are very important to distinguish closely related species, e.g., in the X. argentatus complex, or X. riedli sp. nov. from X. singaporensis Andersen, 2000 . In contrast, the small genitalia offer little help for species identification; usually there are only discrete differences in the paramere shape. In females, the main differences are found on the dorsum of the abdomen; besides setiferation, the relative width of tergites can be used for species differentiation. The terminal structures of females are simple.
Habitats. The restriction to mangroves and swampy saline environments ( Nypa swamps) strongly contrasts with the habitats of other marine Haloveliinae . An exception is Xenobates seminulum ( Esaki, 1926) , which has been reported from open offshore waters at considerable distances from the edge of the mangrove front (PඈඅΗൾආඎඌ & PඈඅΗൾආඎඌ 2006). The typical habitats of Halovelia are rocky shores, mostly coral reef flats. The same habitat is inhabited by a few species of Haloveloides (in Haloveloides s.str.), but most species are found in the intertidal section of rivers.
Distribution. Indo-West Pacific. From Sri Lanka to New Caledonia (Aඇൽൾඋඌൾඇ 2000).
Key to the Philippine species of Xenobates View in CoL (except for the X. argentatus View in CoL complex)
1 Mesofemur with row of long setae at extensor side (MfHI> 1.1; Figs 13–15 View Figs 9–26. 9–12 ). Silvery pilosity on dorsum restricted to few patches ( Figs 1–6 View Figs 1–4 View Figs 5–8 ). ........................... 2
– Mesofemur without row of long setae at extensor side ( Fig. 16 View Figs 9–26. 9–12 ). Silvery pilosity on dorsum strongly extended (e.g., Figs 7, 8 View Figs 5–8 ). ........................ X. argentatus View in CoL complex
2 Antennomeres 2–4 with numerous long setae ( Fig. 9 View Figs 9–26. 9–12 ). Middle legs, especially the mesotarsus short (MLI 1.37–1.64, MsTaI 0.42–0.55). ...... X. nypicola sp. nov.
– Antennomeres 4 without, 2 and 3 without or with very few long setae ( Figs 10–12 View Figs 9–26. 9–12 ); middle legs, especially the mesotarsus long (MLI> 1.71, MsTaI> 0.61). ............ 3
3 Antenna long (AI JJ 0.76–0.84, ♀♀ 0.63–0.71; Fig. 10 View Figs 9–26. 9–12 ). Abdomen of female posteriorly narrow ( Fig. 26 View Figs 9–26. 9–12 ). Anterior sternites of male with distinct medial swelling ( Fig. 24 View Figs 9–26. 9–12 ). ...................................... X. riedli sp. nov.
– Antenna relatively short (AI JJ 0.52–0.61, ♀♀ 0.46– 0.51; Fig. 11 View Figs 9–26. 9–12 ). Abdomen of female broad, troughshaped ( Fig. 6 View Figs 5–8 ). Anterior sternites of male evenly and slightly convex. ............... X. murphyi Andersen, 2000 View in CoL
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