Mesoveliidae, Douglas & Scott, 1867

Watanabe, Kohei, Nakajima, Jun & Hayashi, Masakazu, 2023, Nagisavelia hikarui, a new genus and species of Mesoveliinae (Hemiptera: Heteroptera: Mesoveliidae) inhabiting shingle beaches in Japan, Zootaxa 5353 (5), pp. 468-478 : 477

Key to the species of Mesoveliidae from Japan

The key is applicable to the apterous form and is based on the studies conducted by Esaki (1929), Kanyukova (1988), Polhemus & Polhemus (2000), Damgaard et al. (2012), and Hayashi & Miyamoto (2018). As the following comments indicate, Japanese populations of some species require further study:

Previous Speovelia maritima records should be re-examined because some cases, such as Hayashi (2007) and Wada & Yoshimatsu (2023), N. hikarui sp. nov. may have been confused with S. maritima . Japanese Mesovelia vittigera and M. egorovi records also need to be reviewed taxonomically ( Hayashi et al. 2016): Japanese specimens of M. vittigera differ slightly from those from Europe (see Berchi et al. 2016: figs. 30−31) in the female sternum VIII, with two tubercles at the posterior margin (see Hayashi & Miyamoto 2018: fig. 24D).

Molecular studies suggest the taxonomic status of M. horvathi and M. vittigera in Japan is uncertain ( Damgaard et al. 2012). The synonymy of Mesovelia japonica Miyamoto, 1964 and M. horvathi by Polhemus & Polhemus (2000) is indicated to be doubtful ( Damgaard et al. 2012). DNA sequence data deposited by Muraji & Tachikawa (2000) in GenBank indicated that M. vittigera has a strong affinity with M. furcata Mulsant and Rey, 1852 ( Damgaard et al. 2012).

1. Head very long, length more than 1.8 times longer than width; color royal-orange; eyes small, with dense hairs; labium reached middle of abdomen, antennae and femur without spines...... Nagisavelia hikarui Watanabe, Nakajima et Hayashi , sp. nov.

- Head moderate to long, length less than 1.5 times longer than width; color sordid-brown or yellow-brown to green; eyes reduce or normal, with only two ocular setae; labium reached meso- or metacoxal; antennae and femur with spines............. 2

2. Head long, length about 1.5 times as long as width; color sordid brown; posterior margin of pronotum arched to posterior; mesonotum shorter than pronotum; male abdominal tergum VIII middle of posterior margin slightly depressed ( Figs. 25–30 )........................................................................... Speovelia maritima Esaki, 1929

- Head moderate to long, length subequal or shorter than width; color yellow-brown to green; posterior margin of pronotum nearly straight; mesonotum longer than pronotum; male abdominal tergum VIII middle of posterior margin not depressed.. 3

3. Middle femur without row of spines on posterior margin.......................... Mesovelia horvathi Lundblad, 1933

- Middle femur with row of spines on posterior margin......................................................... 4

4. Posterior margin of hind femur with 1−7 spines; male sternum VIII with two groups of spines........................ 5

- Posterior margin of hind femur without spines; male sternum VIII middle with one group of spines.................... 6

5. Posterior margin of hind femur with 1−4 spines; female sternum VIII with two slender long spines at posterior margin................................................................................... M. thermalis Horváth, 1915

- Posterior margin of hind femur with 3−7 spines; female sternum VIII without spine at posterior margin.............................................................................................. M. miyamotoi Kerzhner, 1977

6. Female sternum VIII without processes (Japanese specimens with two tubercles)............... M. vittigera Horváth, 1895

- Female sternum VIII with two spines at posterior margin.............................. M. egorovi Kanyukova, 1981

Figures

FIGURES 25–30. SEM photographs of Speovelia maritima Esaki. 25–28, Male; 29–30, female. 25, 29, Head to abdomen; 26, thorax and abdomen; 27, habitus; 28, hind tibia and tarsus; 30, abdomen.