Holosoma Semenov, 1889

Gueorguiev, Borislav, 2014, Two new related oodine genera in the Oriental Region, with remarks on the systematic position of the genera Hololeius and Holosoma (Coleoptera, Carabidae), Deutsche Entomologische Zeitschrift 61 (2), pp. 87-104 : 88

Taxon classification Animalia Coleoptera Carabidae

Holosoma Semenov, 1889

Parahololius Heller, 1923: 66 (type species Parahololius weigoldi Heller, 1923)

Parololius Semenov, 1927: 232 [unjustified emendation of Parahololius , not in prevailing usage]

Type species.

Holosoma opacum Semenov, 1889

Historical remarks.

Semenov (1889: 388) proposed the generic name Holosoma for Holosoma opacum from South Gansu, China. The author placed the genus in "subtribum Oodidarum, prope genera Oodes Bon. et Simous Chaud, collocandum" (ibid.: 389). This tribal placement has been subsequently accepted ( Jakobson 1906: 310-311). In 1923, Heller (1923: 66) described the genus Parahololius Heller, 1923, for Parahololius weigoldi Heller, 1923, from Sichuan, China. He placed this genus in Chlaeniini , near to Hololeius . Shortly afterwards, Semenov (1927: 232) proposed [not Basilewsky 1953, as Kirschenhofer 1995: 77 stated] the synonymy of Parahololius and Holosoma and emended the former name to Parololius [according to the Article 32.2.3 of ICZN 1999, the change of the original name to Parololius is an "unjustified emendation]. Jedlička (1931: 21-22) described Holosoma rambouseki Jedlička, 1931 from Sichuan, China. Andrewes (1935) described Chlaenius hedini Andrewes, 1935, from North Gansu and Southeast Sichuan, China. He noted, "It does not appear to be nearly allied to any other Asiatic species." [of Chlaenius Bonelli, 1810]. Jedlička (1936: 51) described Holosoma boettcheri Jedlička, 1936, from the Philippines, which is the only known extra-Palaearctic record for the genus. Subsequent authors dealing with the genus, except for Lorenz (2005), have omitted this species. I have seen the holotype of Holosoma boettcheri in BMNH and found that it belongs to a different group of Oodini . Later, Basilewsky (1953: 153) included Holosoma to the tribe Simoini Basilewsky, 1953, of subfamily Oodinae (sensu Jeannel, 1949a). Kirschenhofer (1995) reviewed the known species (excl. Chlaenius hedini and Holosoma boettcheri ), adding three more species and retaining the tribal affiliation of the genus. Later, he synonymized one of his added taxa with Holosoma hedini ( Kirschenhofer 1998). Recently, Ito (2003, 2012) added five more species and one subspecies to the genus and keyed all species known at that time. He retained the position of the genus within the Oodini .

Taxonomic position.

The discussion here is based on all the generic and species descriptions ( Semenov 1889, Heller 1923, Jedlička 1931, Andrewes 1935, Kirschenhofer 1995, Ito 2003, 2012) and on the detailed examination of two specimens. It considers only the characters that are significant for the tribal position of Holosoma . Excluding Holosoma boettcheri , I am aware that the group is homogeneous and the main structural features are uniform among the species.

Pronotum posterior margin as wide as basal margin of elytra, thus habitus seems semi-oval rather than elongate. Atypical of Chlaeniini (but occurs in a few species, such as the Nearctic Chlaenius tomentosus (Say, 1823); remark by R. Davidson). Typical of Oodini , except for the new genera. This condition is probably a derived trend within the genus because it occurs in most, but not all, species.

Body dorsally with metallic lustre (greenish, turquoise, bluish, violet to black-blue) on dorsal surface. Habitual to Chlaeniini , since many species from this tribe are metallic colored. In the Oodini , a metallic hue is present only in Bamaroodes gen. n., most species of Simous and a few taxa of Stenocrepis Chaudoir, 1857.

Integument sparsely pubescent dorsally and ventrally. The character is distinctive of Chlaeniini , but it is unknown in the Oodini . In the species of Holosoma , the dorsal surface of the head, antennomere 3 (excl. apical setae), pronotum, intervals 8-9 of elytra, prosternum, mesepisternum, mesocoxa, mesofemur, metasternum, metepisternum, and abdomen all have rather fine and scattered punctures (see also Kirschenhofer 1995, Ito 2003). Most of the punctures are provided with short, yellowish hairs, usually well visible under higher magnification. Sparse pubescence is also present on the medial elytral intervals posteriorly, though it is much more sporadic than on the intervals 8-9.

Labrum with six setae along anterior margin. This feature is typical of Chlaeniini . Although it is present in most Oodini , several groups have different setation of the labrum.

Clypeus with a pair of setae. The condition is usual for Chlaeniini . Although it occurs in most Oodini , several groups lack clypeal setae.

Penultimate labial palpomere with 2-4 spines at front margin. Indicative of Chlaeniini (occurs in the most of the species). This feature is unknown in the Oodini . Jedlička (1931: 22) has noted that the penultimate labial palpomere in Holosoma rambouseki lack setae, but this fact needs verification.

Terminal labial palpomere with a few fine and short setae on lateral margin (see also Ito 2012: 303). Occurs in some Chlaeniini . Unknown in the Oodini .

Elytral stria 8 shallower than, or as deep as striae 1-7. Typical of Chlaeniini , except for Hololeius . All taxa of Oodini I have studied have stria 8 more or less grooved along its extent and deeper than other striae.

Discal setiferous punctures situated in elytral intervals 3 and 5, or in intervals 3, 5 and 7. There is no data for this condition in Chlaeniini , but it is also atypical of Oodini . Like point 1, it can be an apotypic trend within the genus since it occurs in several, but not in all species of Holosoma . For example, Holosoma hedini , Holosoma heros Kirschenhofer, 1995, and the specimens from Wenxian possess setiferous punctures in intervals 3, 5 and 7. Holosoma namikoae Ito, 2012, has such punctures only in intervals 3 and 5, and Holosoma rambouseki solely in interval 3. Discal punctures are lacking in Holosoma opacum , Holosoma nigritum Ito, 2003, Holosoma imurai , Holosoma speciosum Ito, 2003, and Holosoma misaoae Ito, 2012. This character has not been described for Holosoma weigoldi .

Elytral intervals 7 and 8 separate (e.g., not fused) posteriorly, thus stria 7 perceptible to apex. Typical of Chlaeniini . Unusual for Oodini , except for Bamaroodes gen. n.

Elytral interval 8 not forming ridge laterally. Typical of Chlaeniini . Unusual for Oodini , except for Bamaroodes gen. n.

Tarsomere 5 of all legs setose ventrally. Typical of Chlaeniini . Unusual for Oodini , except for the two new genera and a few species of Systolocranius . Among the species of Holosoma , the number of the setae varies from two to six on each side of tarsomere 5.

Quinone-like smell defensive secretion. This is one of three groups of compounds used for defence in the Chlaeniini . It is not found in Oodini . Ito (2003: 95) noted that the defensive chemical in Holosoma is "also the same as that of the genus Chlaenius ". I noticed this pungent smell many times when was taking the specimens from Wenxian out of the test-tube and handling them. The odor is identical or similar to that existing in the European species of Chlaeniellus Reitter, 1908 ( Bousquet 1987). Moore (1979: 198-199) regarded the quinones as one of the most elaborate defensive strategies in the ground beetles.

Thirteen character states are considered. Number 9 is not counted due to deficient data about its presence among other taxa. Six character states, i.e., 2, 3, 6, 7, 8, 13, are typical for Chlaeniini and are unknown to Oodini . Characters 10, 11 and 12 are also typical of the Chlaeniini and have a few exceptions in the Oodini . Similarly, characters 4 and 5 are always indicative of Chlaeniini . Most genera and species of Oodini also share these two conditions, but there are some important exceptions. Character 1 is the only one characteristic of Oodini and not typical of Chlaeniini .

In conclusion, Holosoma lacks oodine characters but does share important traits with the chlaeniines. It is therefore removed to a new tribal placement incertae sedis within Chlaeniini . The precise affinity of the genus within the tribe remains unresolved.