First records of three exotic giant mantid species on the Croatian coast

Some giant mantid species of the genera Sphodromantis Stål, 1871 and Hierodula Burmeister, 1838 have been found spreading their distribution through the Palearctic, but none of the species have been recorded from the Adriatic coast of Croatia, where numerous local species already co-exist, such as Mantis religiosa (Linnaeus, 1758) and Iris oratoria (Linnaeus, 1758). In this study, we present the first records of the giant African mantis ( Sphodromantis viridis (Forskål, 1775)), the Indochina mantis ( Hierodula patellifera Serville, 1839), and the giant Asian mantis ( Hierodula tenuiden- tata Saussure, 1869) from Croatia. A small population of S. viridis was observed in the southernmost county of Croatia (Dubrovnik); a single record of H. patellifera comes from the westernmost part of the country (Istria), while the first two specimens of H. tenuidentata were observed in the central part of the Croatian coast (Šibenik). These alien species represent three new taxa for the mantid fauna of Croatia, which now counts 9 or 10 species (depending on inclusion of Ameles heldreichi Brunner von Wattenwyl, 1882). The fast spreading of these species in Europe proves their adapta- tion to regions where they have arrived; thus, future monitoring of the species must be conducted in order to determine their impact on native fauna.


Introduction
Mantids are large predatory insects, so people have been observing them from prehistory (Battiston et al. 2010, Kolnegari et al. 2020). More than 2500 species are known (Otte et al. 2021), with the greatest diversity being in the tropical regions (Schwarz andRoy 2019, Otte et al. 2021). Mantid fauna of the Western palearctic consists of about 130 species (Battiston et al. 2010), while, for example, Vietnam is home to almost 70 species (Shcherbakov and Anisyutkin 2018). Few species are shared between tropical and temperate regions; this study shines the spotlight on three.
Until now, small Croatian Mantodea fauna consisted of seven species belonging to five genera (Ameles Burmeister, 1838, Empusa Illiger, 1798, Geomantis Pantel, 1896, Iris Saussure, 1891and Mantis Linnaeus, 1758 (Rebrina et al. 2014), but the giant African mantis (Sphodromantis viridis (Forskål, 1775)), the Indochina mantis (Hierodula patellifera Serville, 1839), and the giant Asian mantis (Hierodula tenuidentata Saussure, 1869) are expected to spread into the country soon. S. viridis is widespread in the sub-Saharan region and is known to be very adaptable to different kinds of environments, including anthropized ones (Battiston et al. 2020a). In Europe, it was known only from Southern Spain (Bolívar 1876, Gangwere and Morales Agacino 1970) until it was recorded in Mallorca (Canyelles and Alomar 2006) and in Central Spain (Cabanillas 2017) and eventually Portugal (Marabuto et al. 2014, Oliveira andFerreira 2019), France (Battiston et al. 2020a), Italy (Battiston et al. 2017(Battiston et al. , 2020a, and Greece (Battiston et al. 2020a). On the other hand, H. patellifera and H. tenuidentata are native to Asia. The first European records of the former species date back to 2013 in Southern France (Moulin 2020) and 2015 in Italy (Battiston et al. 2020a); the earliest European record of the latter was from Crimea (Werner 1916), where it was rediscovered 100 years later. It is now widespread along the entire coast of the peninsula, from where it started its expansion northwards in other parts of Ukraine (Pushkar and Kavurka 2016). Soon after, European records of H. tenuidentata began to be reported frequently. Today, the species is known to be present in Bulgaria and Greece (Romanowski et al. 2019), Albania (van der Heyden 2018), Italy (Battiston et al. 2018), North Macedonia (Cianferoni et al. 2018), Serbia (Vujic´ et al. 2021), and Romania (Pintilioaie et al. 2021). This study provides further insight into the spread of these species in Europe.

Materials and methods
Hierodula patellifera finding.-A single female was found in Novigrad (Istria) on a palm tree near a road edge. The specimen was photographed and uploaded to Biologer (an open platform for collecting biodiversity data) (Popovic´ et al. 2020).
Hierodula tenuidentata findings.-Two adult specimens were observed and photographed in the garden center "Dubrava" in Dubrava near Šibenik.
Sphodromantis viridis findings.-In early November 2020, an adult male was attracted to the terrace light of a family home on Lapad peninsula in Dubrovnik. The specimen was collected, dry pinned, and deposited in the Dubrovnik Natural History Museum (DNHM). When preparation of the manuscript began based on this single male, the authors were convinced that the male individual represented the only record until it was decided to search the surrounding area for oothecas. Archival photos revealed sighting of a spherical ootheca from November 2019 observed on Nerium oleander L. in a camping area close to where the adult male was collected. The camping area ( Fig.  4G) was visited again in March 2021, and another ootheca was found.
Online records.-iNaturalist was searched for specimens that could represent Sphodromantis or Hierodula specimens, and a single photograph depicting a nymph unidentifiable to species level was found (https://www.inaturalist.org/observations/53351490).
Identification and systematics.-The collected specimens were identified based on the morphological characteristics described in Battiston et al. (2019Battiston et al. ( , 2020b. At first glance, giant mantids of the genera Sphodromantis and Hierodula can be distinguished from the native, similarly sized Iris oratoria (Linnaeus, 1758) or Mantis religiosa (Linnaeus, 1758) by the presence of white-colored stigmas on the tegmina (Figs 2A, 3A, 4C). Both species of the genus Hierodula spreading through Europe (H. patellifera and H. tenuidentata) have three dark-colored horizontal lines on the ventral part of the thorax (Fig. 2B), which are absent in S. viridis (Fig. 4A). Additionally, differences exist in the shape and length of the pronotum, which is long and thin in Sphodromantis (Fig. 4B) but short and ovoidal in Hierodula (Fig. 3A). The two Hierodula species may be separated by the morphology of the inner margin of the anterior coxa. In H. patellifera, it is equipped with yellowish spines with basal plates (Fig. 2B, C), while basal plates are absent in H. tenuidentata (Fig. 3B). The higher systematics follow Battiston et al. 2010, while species nomenclature follows the Mantodea species file (Otte et al. 2021). In the literature, H. tenuidentata is sometimes reported under its synonym, T. transcaucasica. Most probably, H. tenuidentata Journal of orthoptera research 2022, 31 (1) represents a single species distributed from India to Europe (Battiston et al. 2018).

Family Mantidae Burmeister, 1838
Composition and distribution in Croatia.-Hitherto, at least four species belonging to three genera (Ameles, Mantis, Geomantis) have been reported from the country (Rebrina et al. 2014). In current taxonomy (Schwarz and Roy 2019), Ameles belongs to Amelidae; thus, it is no longer included in Mantidae, so the following checklist includes members of both families in the Croatian fauna. Distribution follows data from Rebrina et al. (2014), GBIF (2021), and iNaturalist (2021). This study presents the first records of members of two more genera, Hierodula and Sphodromantis, found to be present in Croatia.

Genus Sphodromantis Stål, 1871
Species S. viridis (Forskål, 1775), newly reported for the country (Fig. 4).   Taxa not identified to species level.-Besides the new records identified to species level, a juvenile specimen was observed on 13 th July 2020 by Dennis Aagaard in a small tourist area called Zaton near Zadar; the photo was published on iNaturalist (observation number 53351490). The nymph in the photo has its abdomen bended at an angle of 90°, which is a diagnostic character related to the juvenile stages of both S. viridis and Hierodula species. Nymphs of M. religiosa have the abdomen held parallel to the ground from the first to the last moult . Although not identifiable to the species level from the photo, this record signals the possibility that H. tenuidentata Saussure, 1869 is already widespread in Dalmatia. More records are anticipated soon.

Discussion
Finding a single male of an allochthonous mantid species could be overlooked, but finding two oothecas at the same place two years apart suggests that a small population of S. viridis has been established in Southern Croatia (Fig. 4F). Dubrovnik is on the itineraries of many cruise ships, and it is included in both Western and Eastern Mediterranean cruise routes. During their round-trip excursions, some cruise ships visit several port cities in southern Spain, France, Italy, Cyprus, Turkey, and Greece, which are already inhabited by S. viridis, before arrival in Dubrovnik. The cruise-ship route probably served as a pathway of introduction for S. viridis to Croatia. The locality where the small population of S. viridis was recorded is situated on the Lapad peninsula, right at the entrance to the Port of Dubrovnik. The species is likely attracted to the lights of ships staying the night in the Mediterranean ports within the species' distribution area; in this way, they arrive in Dubrovnik as a blind passenger, either from the western Mediterranean (Southern Spain) or from the Middle East (Cyprus, Turkey). This hypothesis is in accordance with insights on the human-assisted speed of expansion of S. viridis across the Mediterranean region (Battiston et al. 2020a). However, there are many other plausible causes. For example, oothecae may have come attached to plants or other commercial goods or attached to tourists' cars or personal items. Finding two specimens of H. tenuidentata in the garden center "Dubrava" in Dubrava near Šibenik (Fig. 3C) adds credence to the possibility of human-assisted expansion of this species in Europe, as the garden center sells plants imported from various areas in Italy where H. tenuidentata is known to be present (Battiston et al. 2018). Unfortunately, a lack of evidence means we can only propose hypotheses to be tested by future dispersals within the region. We will continue to monitor the garden center in order to assess whether the species already has the population established.
As in France and Italy where individuals of H. patellifera were observed mainly on trees (Battiston et al. 2020b, Moulin 2020, the female specimen found in late November 2020 on a palm tree is further confirmation of the arboreal habits of this species. The arrival of H. patellifera in the westernmost part of the Croatian Adriatic (Fig. 2D) is likely a result of natural dispersal from the neighboring Northern Italy where several fragmented and reproducing sub-populations exist (Battiston et al. 2020b).
There is currently no evidence of invasive behavior from these alien species. However, they have only been present for a short period, and their impact on local fauna should be determined by detailed research conducted over the span of many years. Comparative studies are needed to determine whether Hierodula and Sphodromantis represent direct competition to Mantis, Iris, or Empusa. Sphodromantis is not expected to spread much, as it prefers habitats influenced by the Mediterranean climate. Hierodula species are, however, expected to spread more, considering that H. tenuidentata is already surviving the cold Pannonian winters in Serbia (Vujic´ et al. 2021). On the other hand, the native area of distribution of H. patellifera includes localities with similar climate, such as that of Northern Italy and Central Europe (Battiston et al. 2020b). Thus, Hierodula can be expected to colonize the Mediterranean, Pannonian, and the Dinaric region.