New synonymies in Sphecodes Latreille, 1804 (Hymenoptera, Apoidea, Halictidae) species from Italy, with taxonomic notes on type material

Type specimens of the bee genus Sphecodes Latreille, 1804 (Hymenoptera: Halictidae), described by Vittorio Nobile and Giuseppe Fabrizio Turissi from Italy and deposited in the Zoologische Staatssammlung, München, Germany, were studied. Detailed information on the primary types of the six nominal species and their illustrations are provided. Sphecodes banaszaki Nobile & Turrisi, 2004, syn. nov., S. marcellinoi Nobile & Turrisi, 2004, syn. nov., S. walteri Nobile & Turrisi, 2004, syn. nov., S. iosephi Nobile & Turrisi, 2004, syn. nov., and S. tomarchioi Nobile & Turrisi, 2004, syn. nov., are all synonymized with Sphecodes combai Nobile & Turrisi, 2004, which is rediagnosed. Also accepted synonymy of S. campadellii Nobile & Turrisi, 2004 = S. geoffrellus (Kirby, 1802), previously suggested by M. Schwarz’s and F. Gusenleitner’s (2012).


Introduction
One of controversial problems in the taxonomy of European species of the genus Sphecodes Latreille, 1804 (Hymenoptera: Halictidae) is the status of the species described by Italian researchers V. Nobile and G.F. Turrisi (2004) from Italy. They described seven new species (each from a single male), attributing them to the Sphecodes pinguiculus  species group. It was not surprising that the description of several new species from this difficult genus at once in within a fairly well-studied European fauna (four of them from the same type locality) attracted attention. A few years later their type specimens were examined by Austrian researchers M. Schwarz and F. Gusenleitner (2012). As a result, they were all synonymized with two other widespread Palaearctic species: S. campadellii with S. geoffrellus (Kirby, 1802, and the other six species, S. combai , S. banaszaki Nobile & Turrisi, 2004, S. marcellinoi Nobile & Turrisi, 2004, S. walteri Nobile & Turrisi, 2004, S. iosephi Nobile & Turrisi, 2004, and S. tomarchioi Nobile & Turrisi, 2004with S. marginatus Hagens, 1882 Nevertheless, a year later, that taxonomic action was challenged by the authors of the Italian species (Nobile and Turrisi 2013), who restored their valid status. Jakub Straka (Prague, Czech Republic) also studied these types; he was convinced that only S. combai is a distinct, valid species from the S. marginatus species group (personal communication of J. Straka); however, he did not publish that in the review of the European Sphecodes, see Bogusch and Straka (2012: 2). Sphecodes combai occurs in Italy from Sicily all the way north to the border with Switzerland, and was also found in Greece (Bogusch and Straka 2014).
Thus, there are several points of view on the taxonomic status of the Sphecodes species described by Nobile and Turrisi (2004), so we decided to readdress this matter. We reexamined the holotype specimens of S. combai, S. banaszaki, S. marcellinoi, S. walteri, S. iosephi, and S. tomarchioi in Zoologische Staatssammlung, München, Germany (ZSM). The holotype of S. campadellii was stated in the original description as being deposited in the Istituto di Entomologia, Università di Bologna, Italy (IUB); however, it has not been found either there (personal communication of G.F. Turrisi) or in ZSM (personal communication of O. Schmidt), although the later depository was mentioned by Schwarz and Gusenleitner (2012) and Nobile and Turrisi (2013).
We agree with the opinion of J. Straka about the validity of S. combai and also accept M. Schwarz's and F. Gusenleitner's point of view that the holotype specimens of the other five Italian species (except S. campadellii) are conspecific with it, hence the proposed new synonymies.

Materials and methods
The ventral surface of some flagellomeres bear a distinctive patch of sensilla trichodea A (sensu Årgent and Svensson 1982), which we refer to as 'tyloids', these sensilla are easily observable under a microscope. Abbreviations F and T are used for flagellomere and metasomal tergum, respectively. Density of integumental punctures is described using the following formula: puncture diameter (in μm) / ratio of distance between punctures to average puncture diameter, e.g., 15-20 μm / 0.5-1.5.
Specimens were studied with a Leica M205A stereomicroscope and photographs were taken with a combination of stereomicroscope (Olympus SZX10) and digital camera (Olympus OM-D and Canon EOS70D). Final images are stacked composites using Helicon Focus 6 software. All images were post-processed for contrast and brightness using Adobe Photoshop.  Fig. 7B, C). This character was also pointed out by Nobile and Turrisi (2013) as a clearly distinguishing one from S. marginatus. Another important feature mentioned by these Italian researchers is the gonostylar shape. Although being very similar in these two species, in S. marginatus it is relatively smaller and close to the triangular membranous portion of the gonostylus (Fig. 7D), distinguishes, S. combai from its trapezoidal membranous portion is larger (Fig. 1E). Thus, its shape is most similar to that in S. nomioidis (Fig. 7E), although the position of the gonostylus or  Although S. pinguiculus and S. intermedius also have a similar T2 with tyloids usually covering the entire ventral flagellar surface (sometimes T2 is entirely or partially glabrous in S. intermedius), S. combai differs from these species by a shorter antenna with flagellomeres being 1.1-1.2 times as long as wide (versus 1.4-1.7, Fig. 7A), a shorter vertex (the distance from top of the head to the upper margin of the lateral ocellus, being about two lateral ocellar diameters as seen in dorsal view, versus 2.5-3), the face above the antennal sockets with sparser and shorter pubescence partially obscuring the integument (versus dense long pubescence entirely obscuring the integument,  Fig. 7A), and a more sparsely and finely punctate T1 with punctures separated by 2-5 puncture diameters (versus at most 2). So, possible placement of S. combai to the S. pinguiculus species group is doubtful and would be premature without taking into account the female morphological features. Besides, morphologically it is more similar to S. marginatus and S. nomioidis, so most likely S. combai belongs to the same group with the latter two species.

Sphecodes combai
Female. The female of S. combai has not been described, but we examined two from Italy (1 ♀, Emilia Romanga, Comacchio, VII.2001, M. Richa, and 1 ♀, Sic- ily, Naxos Strand, 17.V.1961, J. Gusenleitner), both in the personal collection of M. Schwarz, Ansfelden, Austria) determined by J. Straka (in 2012) as S. combai. These specimens are very similar to S. marginatus, but with a relatively denser punctate ocello-ocular area. It is likely that these two female specimens belong to S. combai, thus providing an additional indication that this species is likely to belong to the informal S. miniatus species group. However, we refrain from describing the female sex of this species based on specimens not in the same series with conspecific males. In addition, if the assumption that S. combai belongs to the S. miniatus species group is correct, then the female of S. combai may have very weak morphological differences from the other members of this group. Therefore, description of the other sex of S. combai may also require additional genetic evidence, which is now unfortunately lacking for both sexes.
Synonymy. Most species of Sphecodes exhibit a considerable intraspecific variation. While studying numerous specimens from various parts of the Old World we have observed variation in the body size, sculpture, coloration, and sometimes degree of development of the tyloids and relative length of the flagellomeres. Intraspecific versus interspecific variation in body size Sphecodes is an interesting topic that warrants a further, thorough investigation, including using molecular methods.
Indicated differences between the seven nominal species described by Nobile and Turrisi (2004) were based on sculpture (of the vertex, frons, T1), coloration (of the mandibles, antennae, metasoma and legs) and the gonostylar shape. We have reexamined the holotypes of S. banaszaki, S. tomarchioi, S. iosephi, S. walteri, S. marcellinoi, S. combai and concluded that the minor morphological differences between them can be considered as intraspecific variation, as also pointed out by Schwarz and Gusenleitner (2012).
The main differences between the primary type specimens examined are outlined in Table 1. The holotype of S. marcellinoi has a sparser punctation on the upper half of the frons; tergal coloration of the holotype of S. combai is lighter and reddish; the holotype of S. banaszaki is larger (6 mm versus 4-5 mm) and with coarser and denser T1 punctation; the holotype of S. iosephi has a denser punctate ocello-ocular area and mandibles medially dark yellow (not entirely black as incorrectly indicated in the original description). The slight differences in the gonostylar shape, as illustrated by Nobile and Turrisi (2004), are the result of a deformation and different position of the gonostylus relative to the axis of genitalia, see also Schwarz and Gusenleitner (2012).
On the other hand, such a rare feature as F2 with tyloids covering the entire ventral flagellar surface not only distinguishes the six nominal species of Sphecodes described by Nobile and Turrisi (2004) from Italy from the other Palaearctic species quite well, but also more likely (also based on their morphological similarity) indicates their conspecificity within S. combai. Table 1. Differences of Sphecodes combai from other species of the S. miniatus species group described by Nobile and Turissi (2004).