Aplocnemus (Ischnopalpus)

Liberti, Gianfranco, 2019, The Aplocnemus Stephens, 1830, of Greece (Coleoptera, Cleroidea, Dasytidae). A contribution to their knowledge, Natural History Sciences 6 (1), pp. 3-26 : 7-8

Aplocnemus (Ischnopalpus) ; type species A. (Ischnopalpus) subcostatus Schilsky, 1894 , by subsequent desi- gnation (Schilsky, 1894a: 62).

Shortly afterwards Pic (1896: 47) added a fifth sub- genus:

Aplocnemus (Pseudaphictus) ; type species A. tournieri Pic, 1896 by monotypy (see also Peacock, 1987: 152).

These five subgenera have been accepted by Schilsky (1897), Pic (1937) and Peacock (1987). The paper of Peacock (1987) is a nice revision of the whole subfamily Rhadalinae with excellent illustrations, however she do- es not discuss the Aplocnemus subgenera and lists all the species together in alphabetical order.

A couple of decades later Constantin (2005: 219) synonymized Aplocnemus (Pseudaphictus) with Aplocnemus (Aplocnemus) , a proposal fully shared by the writer because the subgenus was created only based on elytral shape – namely humeral callous reduced to absent, elytra rounded and widened in the middle – which is not structu- ral but simply linked to apterism (or to reduced wings).

Aplocnemus (Diplambe) has been defined (Schilsky, 1894b: 234) on the ground of the lateral elytral border appearing double [due to the presence of a “sublateral carina in basal half, forming a double elytral edge” (Peacock, 1987: 136)]: a well evident character shared with Rhadalus LeConte, 1852 (Peacock, 1987: Fig. 16). Furthermore in A. ( Diplambe ) phallobase and parameres are not fused together and appear connected by membranous tissues (Fig. 50; see also Majer, 1987: Fig. 212), a character shared by genus Trichoceble Thomson, 1859 (Liberti, 2012: Figs. 8, 28, 39, 43).

Aplocnemus (Ischnopalpus) has been defined mainly on the ground of maxillary palps last article which is spin- dle shaped instead of being securiform (Peacock, 1987: Figs. 31, 32). Schilsky (1897: 34 BB) also suggests a couple of further characters: dorsal surface black and strongly punctuate and longer epipleura, but these are not always fully valid [as for example A. (Ischnopalpus) gracilicornis Schilsky, 1897 ]. However the validity of Ischnopalpus, possibly up to generic level, is also supported by the aedeagus shape, characterized by an overdeveloped tegmen enveloping a smaller median lobe (Figs. 15, 17, 18; see also Majer, 1987: Fig. 205) while in A. ( Aplocnemus ) the tegmen is placed astride a well developed median lobe (Figs. 16, 20). Also note the Ischnopalpus spicular fork apically strongly bent dorsally, against the Aplocnemus one which is moderately bent.

On the other hand A. ( Holcopleura ), established by Schilsky (1894b: 234, 1897: 34 BBB) for A. reitteri , was based on just one character: the propleura (“Pleuren des Halsschildes”) fitted with a transverse impression (“quer- furche”); namely the front legs coxal grooves extend, al- though with reduced depth, nearly up to the lateral sides. But this character is often unclear, difficult to apprecia- te and can be (more or less) detected only in A. reitteri . In Greece three more species resembling A. reitteri can be found: A. caelatus , A. cribrarius and A. henrici . These four species show evident similarities and compose a homogeneous group: in spite of that the writer was not able to find any definite, clear cut differential character common only to these species, to support the Holcopleura subgenus validity (the Schilsky’s “querfurche” appears, to the writer, inadequate; see also the discussion below). For this reason, the synonymy with A. ( Aplocnemus ) is here proposed:

Aplocnemus subgenus Holcopleura Schilsky, 1894 = Aplocnemus subgenus Aplocnemus Stephens, 1830 syn. n.

Aplocnemus (Aplocnemus) are characterized (Schilsky, 1897: 34 BB) by variable, more or less securiform, truncated last article of maxillary palpi (Peacock, 1987: Fig. 31) and simple elytral lateral border.

Considering the maxillary palpi last article, in its pre- sent meaning subgenus Aplocnemus includes species with apical edge longer than internal edge (largely securiform) as well as others where apical edge is as long as (or even shorter than) internal edge (less evidently hatchet shaped); a number of species also have (males) with a round, finely pubescent impression on first and (often) second visible sternites (Constantin, 2005: Fig. 6). These two characters are (to some extent) related: species with the round impression on sternites also show clearly securi- form last palpi article; on the other hand species with sim- ple sternites also have last palpi article “less securiform” (namely longer with shorter apical edge). The latter case include our four species: A. caelatus , A. cribriarius , A. henrici and A. reitteri , together with many others (as, for example, A. cylindricus Kiesenwetter, 1863 , A. angelinii , A. jejunus and others). It might be that, in the future, subgenus Aplocnemus could be split taking these characters into account (in the writer’s opinion these criteria are, anyway, well outside the definition of the Schilsky’s sub- genus Holcopleura ).

As a conclusion, three out of the four Schilsky’s subgenera, namely A. ( Aplocnemus ), A. ( Diplambe ) and A. (Ischnopalpus) show good differential external charac- ters as well as important aedeagical differences: they are deemed to be valid and are here accepted. Whether they should be considered subgenera, or should be raised to good genera, is beyond the scope of the present paper.

Table 1 summarizes the main differences between the three valid subgenera: A. ( Aplocnemus ), A. ( Diplambe ) and A. (Ischnopalpus) (however please note that no Ischnopalpus lives in the territory here considered).

* = A. (Ischnopalpus) subcostatus Schilsky, 1894, type species of this subgenus, has been here chosen as representative. It is very common in Morocco, from the sea level to over 2000 m elevation (original, unpublished data). But taxonomy is uncertain [it might be a possible synonym of A. (Ischnopalpus) morio (Schönerr, 1817)] and this name may turn out, in the future, as incorrect .