Krateraspis Lignau, 1929

Dyachkov, Yurii V. & Bonato, Lucio, 2022, Morphology and distribution of the Middle Asian centipede genus Krateraspis Lignau, 1929 (Chilopoda, Geophilomorpha, Mecistocephalidae), ZooKeys 1095, pp. 143-164 : 143

Krateraspis Lignau, 1929

Krateraspis : Lignau 1929a: 160 (available name), 165. Lignau 1929b: 207 (original description). Verhoeff 1930: 265. Titova 1975: 39, 46 (in key). Titova 1983: 148. Bonato et al. 2003: 544, 547, 549, 550, 552, 553. Foddai et al. 2003: 1255. Bonato et al. 2009: 195, 199, 207. Bonato et al. 2010a: 515. Bonato and Zapparoli 2011: 331. Bonato 2011: 434. Volkova 2016: 675. Dyachkov 2019: 368, 370, 372. Dyachkov 2020: 79; Dyachkov and Nedoev 2021: 44.

Type species.

Mecistocephalus meinerti Sseliwanoff, 1881, by monotypy ( Lignau 1929a, 1929b).

Remarks on nomenclatural issues.

The genus name Krateraspis was first introduced by Lignau (1929a) without a description or diagnosis, but it was explicitly used for the species Mecistocephalus meinerti Sseliwanoff, 1881 and therefore it is available since that publication (ICZN 1999: Art. 12.2.5). Instead, the first morphological description of Krateraspis was given in a different paper by the same author, published in the same year but in a later date ( Lignau 1929b).

The type species of Krateraspis was determined by monotypy (see also Jeekel 2005: 86), not by original designation as erroneously reported by Bonato et al. (2016) and Dyachkov (2019).

Diagnosis.

A genus of Mecistocephalidae with: anterior areolate part of the clypeus extending along the lateral margins of the clypeus to the labrum; two clypeal plagulae separated by a mid-longitudinal areolate strip; central part of the clypeus with distinct but fainter areolation in comparison with the markedly areolate anterior part and the mid-longitudinal strip; clypeal setae only three or four pairs, on the antero-central part of the clypeus; buccae without spiculum; labral anterior ala with the internal margin reduced to a point; labral posterior ala with the posterior margin entire, without bristles; coxosternite of first maxillae divided by a mid-longitudinal suture; coxosternite of second maxillae entire, without mid-longitudinal suture, with the grooves from the metameric pores reaching the lateral margins of the coxosternite at approximately their mid-length; telopodite of second maxillae bearing a small claw-like pretarsus; forcipular tergite slightly wider than long; sternites without pore fields; either 45 or 53 pairs of legs; ultimate legs without claw but with an apical small spine.

Krateraspis differs from other mecistocephalids (Table 1 ) mainly in the pattern of clypeal areolation and setation: a broad weakly areolate central part of the clypeus is distinguishable from the distinctly areolate anterior part as well as the non-areolate posterior plagulae, and a few setae are present on the medial part only. Of two other Middle Asian mecistocephalid genera, Tygarrup and Arrup , Krateraspis is more similar to the former. Tygarrup differs from Krateraspis for an entire non-areolate plagula lacking a mid-longitudinal areolate strip, and for the presence of setae on both the central and lateral parts of the clypeus. Arrup differs from Krateraspis not only in the clypeus (markedly areolate in both the central and anterior part, with setae on the both the lateral and central parts), but also in the maxillary complex (coxosternite of the first maxillae entire, without mid-longitudinal suture; coxosternite of the second maxillae with grooves from the metameric pores running backwards towards the posterior corners of the coxosternite), in the forcipular tergite (much wider than long), and the number of legs (41 pairs).

Included species.

Krateraspis meinerti (Sseliwanoff, 1881) and K. sselivanovi Titova, 1975.

Distribution.

Recorded from 24 localities in Middle Asia so far, from Western Tian-Shan to the western offshoots of Pamir Mts (Fig. 1 ).

Remarks on published morphological accounts.

The peculiar pattern of clypeal areolation is well recognizable only using a light microscope with slides, while it is very poorly visible using stereo (dissecting) microscope. Additionally, the semblance of the areolation is conditioned by the preparation of the specimen, the optical properties of the inclusion medium and the mode of illumination. This may explain why the pattern of areolation on the clypeus has been interpreted, described, and illustrated in inconsistent ways by different authors. Lignau (1929b) did not distinguish between a markedly areolate anterior part and a weakly areolate central part, neither in the textual description of K. meinerti ("Vorderklypeus fein gefeldert, nimmt etwas mehr als die Hälfte der gesammten Fläche ein" [anterior clypeus finely areolate, extending a little more than half of the total area]) nor in the associated illustration (his fig. 10). In the same way, Titova (1975) described K. sselivanovi without indicating any variation in the areolation between anterior and central parts of the clypeus, neither in the textual description ("Peredniy clypeus zanimaet bolee poloviny nalichnika, ego poverhnost sostoit iz polygonalnikh poley, po seredine uzkoy polosoy razdelyayuschikh zadniy clypeus na 2 poloviny" [anterior clypeus covers more than a half of the total clypeal area, its surface consists of polygonal cells that divide the posterior clypeus in the middle into 2 parts by a narrow strip], nor in the accompanying illustration (her fig. 2: 1A). On the other hand, Verhoeff (1930) described and illustrated T. asiaticus (synonym of K. meinerti , see below) ignoring the weak areolation in the central part of clypeus and assigning this part to the non-areolate plagulae. Dyachkov (2019) used term “insula” for the weakly areolate central part of the clypeus of K. meinerti , but the term was previously used for a non-areolate area inside the areolate anterior clypeus ( Bonato et al. 2010b).

The pattern of clypeal setae and sensilla has also been reported inconsistently: the eight “Punkte” [points] described and illustrated by Lignau (1929b: fig. 10) in the central part of clypeus of his single specimen of K. meinerti are probably the sockets of broken setae, because these points (in his fig. 10) correspond in number and position with the eight clypeal setae present in most specimens of this species. In the same way, Lignau (1929b) described the antennae as “kahl” [without setae] probably because the antennal setae were broken in his material.

The description of K. meinerti provided by Lignau (1929b) includes another obvious mistake: the sentence "2. Maxille mit getrennten Hüften” [second maxillae with divided coxosternite] should be read "1. Maxille mit getrennten Hüften” [first maxillae with divided coxosternite], because it is contradicted by a previous sentence in the same text ("ganz verwachsenen Hüften der 2. Maxille" [entirely coalescent coxosternite of the second maxillae"], as well as by an associated illustration (his fig. 9).

Figures

Figure 1. Distribution of Krateraspis Lignau, 1929: square, K. meinerti (Sseliwanoff, 1881); star, K. sselivanovi Titova, 1975. Green symbols indicate type localities. Some very close localities are marked by a single symbol. The question marks indicate alternative positions of the uncertain locality " Fayzabad " (see Materials and methods).