Five new species of Pseudomezium Pic (Coleoptera: Ptinidae: Ptininae), a genus endemic to South Africa

Five new species of the South African endemic spider beetle genus Pseudomezium Pic are described from the Western Cape province. They are Pseudomezium altimontanum, Pseudomezium glabrum, Pseudomezium periculum, Pseudomezium stenochasma and Pseudomezium swartbergense . Illustrations of the external morphology and male genitalia of each species are provided, as well as a distribution map. An updated key to all described Pseudomezium species is provided. Four previously established species names in the genus Pseudomezium are corrected because of their Code-incompliance. These names after mandatory nomenclatural correction are Pseudomezium brunneaurantiacum Smiley & Philips for “ Pseudomezium brunneaurant ”; Pseudomezium diteinum Smiley & Philips for “ Pseudomezium diteinus ”; Pseudomezium dolichotrichinum Smiley & Philips for “ Pseudomezium dolichothrixus ”; and Pseudomezium polyomorphum Smiley & Philips for “ Pseudomezium polyomorphus .” The diversity of spider beetles in South Africa is also summarised.


INTRODUCTION
The spider beetles, currently part of the family Ptinidae as the Ptininae, are small, mainly xerophilic beetles that are widely distributed globally and appear to be particularly diverse in sub-Saharan Africa. Worldwide, spider beetles constitute about 70 genera and more than 600 species. The southern part of Africa is one of the major biodiversity hotspots for spider beetles globally, possibly due to the area's geographic uniqueness and great environmental variability (Werger 1978), among other factors. South Africa alone has 22 described genera, 11 of which are endemic, and with still several more known but undescribed (Philips, unpubl.). The paucity of knowledge on this fauna may be due to a combination of factors such as their small size, cryptic form, and small populations with limited distributions for some species (e.g. Gearner et al. 2019), as well as too few taxonomists.
The genus Pseudomezium was erected by Pic (1897) for his new species Pseudomezium sulcithorax, a synonym of Ptinus coquerelii Fairmaire, 1876(Bellés 1985. Pic (1908) described a second Pseudomezium species, namely Pseudomezium schultzei. More than a century later, Smiley & Philips (2011) added another nine species to this genus, showing that species of Pseudomezium are widely distributed through the Western Cape province of South Africa. Towards the end of their study, Smiley & Philips (2011) discovered five additional undescribed Pseudomezium species, but these were left in abyeance. Herein, we describe and illustrate those new species and their distributions and update the identification key initially published by Smiley & Philips (2011). We also publish mandatory corrections to the spellings of four Pseudomezium specific epithets which Smiley & Philips (2011) created in conflict with the requirements of the International Code of Zoological Nomenclature (ICZN 1999).

MATERIALS and METHODS
This study was based upon the 34 specimens from the Ditsong National Museum of Natural History in Pretoria, South Africa. Photographs were taken with a JVC KYF75U camera mounted on either a Leica® MZ16 dissecting scope or an Olympus® BH-2 compound microscope, using the Syncroscopy® automontage system. Genitalia dissections were made after softening specimens in hot water, separating the abdomen from the rest of the body, soaking the abdomen in lactic acid to soften tissues, removing the genitalia and placing them in glycerin. They were then studied and imaged on a microscope slide and later for permanent storage placed in a genitalia vial that is on the same pin as the dissected specimen.
The geographic coordinates on Ditsong National museum of Natural History (TMSA) specimen labels before ca. 2020 are not decimal degrees, but a notation of degrees and minutes that very much looks like a decimal degrees format (R. Stals, pers. comm.). Recorded labels may contain alternative abbreviations and spellings for the same locality. Endrödy-Younga erroneously used the term "groundtrap" instead of pitfall trap; he often left these traps in the field for long periods of time (R. Stals, pers. comm.). Body lengths were measured from the pronotal apex to the elytral apex, with the specimen held horizontally. Body size ranges were calculated by measuring all intact specimens to report the smallest and largest measurements. The length of the pronotum was measured from its anterior margin to the transverse cleft at its base.
All holotypes and most paratypes are deposited in the Ditsong National Museum of Natural History (TMSA), Pretoria, South Africa. Selected paratypes are deposited in the collection of the second author (TKPC), Western Kentucky University, Kentucky, USA. Holotypes and paratypes are respectively labelled with red and yellow type labels. This species can be distinguished from other Pseudomezium species by the following combination of characters: long red-brown pronotal setae slightly lighter-coloured than the surrounding cuticle; pronounced white ovoid setal patches on the apical quarters of the elytra; and long, erect, orange-brown elytral interpuncture setae, the same length as the width of two intervals. Size range: 1.9-2.3 mm

Description
Head. Cuticle dark red-brown; setae predominately orangebrown and occasionally silver on vertex and genae, some with bifid apices; frons medially with smooth patch, a few scattered setae located centrally, other surfaces rugose and densely covered with medium-sized punctures; interantennal ridge as wide as diameter of 2 ommatidia, with few orange-brown, recumbent setae; eye subcircular, maximum diameter approximately ¾ the length of scape; antennomeres 3-10 subequal in size, penultimate antennomere at widest point approximately equal to half its length, ultimate antennomere 1.5 times as long as penultimate, covered with silvery setae. Pronotum. Cuticle dark red-brown; erect or suberect setae red-brown, slightly lighter-coloured than cuticle, fine, long; median lobes large, moderately expanding dorsally, median cleft in dorsal view approximately one half total length of pronotum, inner sides approximately 4-5 elytral punctures wide at narrowest point, parallel at middle, converging very slightly posteriorly, diverging very slightly anteriorly, posteriorly expanding out laterally obliquely to small lateral cleft; lateral spines present; three dorsally projecting basal spines sparsely covered with a thin layer of tan setae, setae absent from spaces between spines. Elytra. Cuticle dark reddish brown to reddish black; interpuncture setae orange-brown, some with bifid apices, in length mostly subequal to width of two elytral intervals and longer than first metatarsomere; surface texture smooth; at second and third puncture rows at middle, punctures separated by a distance 3 times their length, separation of rows approximately equal to width of 5-6 punctures; basal maculation consisting of dense, interrupted bands of coarse, white, recumbent setae; maculation at apical quarter consisting of mostly An ovoid, sometimes slightly transverse, patch of coarse, dense, white, recumbent setae; narrow transverse band of similar setae near apex; elytral margin at apex slightly notched inwards. Male genitalia. Very elongate, parameres very narrow, median lobe elongate and narrow ( Figure 6A).

Etymology
The name is derived from the Latin adjectives "altus" [high] and "montanus" [mountainous], referring to the large elevations at which this species occurs. The specific epithet is an adjective.   This species is easily distinguished from all other known Pseudomezium species known by the elytra lacking basal maculation and the apical maculation being barely visible; and the lack of elytral interpuncture setae. The three dorsally projecting spines on the pronotum are also notably asetose. Size range. 2.3-2.4 mm

Description
Head. Dark reddish-brown; setae predominately orangebrown and occasionally silver laterally on vertex and genae, recumbent, some with bifid apices, vertex surface dorsally and laterally densely rugose, glabrous; interantennal ridge as wide as diameter of 3 ommatidia, setae largely absent; eyes subcircular, at maximum diameter approximately half the length of scape; antennomeres 3-10 subequal in size, penultimate antennomere at widest point approximately equal to half its length, ultimate antennomere 1.5 times as long as penultimate, covered with fine silver setae. Pronotum. Dark red-brown to red-brown; setae orange-brown, fine, long; large median lobes projecting dorsally, median cleft in dorsal view approximately half the length of pronotum measured from anterior margin to transverse cleft at base, inner sides approximately 2.5 elytral punctures wide at narrowest point, inner sides approximately parallel for most of length except near anterior end, posteriorly expanding out laterally obliquely to small lateral cleft, visible from frontal view; lateral spines present; three dorsally projecting basal cleft spines, setae largely absent from lateral spines, and space between spines, much more dense on central spine. Elytra. Dark reddish-brown approaching black; interpuncture setae absent; surface texture smooth to slightly rugose; at second and third puncture rows at middle, punctures separated by a distance approximately equal to 3 times their own length, separation of rows approximately equal to width of 4 punctures; maculation absent from elytral base, minimal on apical quarter, consisting of very few white, recumbent, coarse setae, nearly absent by lateral edges near apex, lacking notch at apex. Male genitalia. Short in length, parameres moderate in width, median lobe moderately narrow to short ( Figure 6B).

Etymology
This name is derived from the Latin adjective "glaber" meaning "bald," referring to the lack of interpuncture setae on the elytra. It is the only known Pseudomezium species lacking interpuncture setae and largely without white setal maculations on the elytra.

Pseudomezium periculum Apostolopoulos & Philips sp. n. Figures 3, 6C, 7 Diagnosis
This species is the only known Pseudomezium to occur the vicinity of Danger Point in the Western Cape. It can be distinguished by the following combination of characteristics: a dense band of white setal maculation on the apical quarter of each elytron and short (approximately the length of the width of 1-1.5 intervals), suberect silver interpuncture setae. The median pronotal cleft shape is nearly identical to that of P. noacanthus Smiley & Philips, 2011, but the latter species lacks lateral pronotal spines. Size range. 1.7-2.2 mm Description Head. Dark brown to reddish-black; setae predominately silvery and occasionally orange, some with cleft tips, recumbent; head surface above antennae on frons largely covered with small shallow impressions, with glabrous patch; interantennal ridge as wide as diameter of 1-2 ommatidia, with few silvery setae; eyes subcircular, at maximum diameter approximately half the length of scape; antennomeres 3-10 subequal in size, penultimate antennomere at widest point approximately equal to half its length, ultimate antennomere 1.25 times length of penultimate, covered with silvery setae. Pronotum. Dark red-brown; setae light brown, fine, long, few with cleft tips; large median lobes slightly expanding dorsad; median cleft in dorsal view approximately half the total length  of pronotum measured from anterior margin to transverse cleft at base, inner sides approximately 1.5 elytral punctures wide at narrowest point, inner sides approximately parallel for two thirds length, slightly diverging posteriad for entire length, slightly expanding out laterally obliquely to small lateral cleft; lateral spines reduced but present; three dorsally projecting basal cleft spines; space between covered with a thin layer of either tan or whitish-yellow setae. Elytra. Black to dark red-brown; interpuncture setae silveryellow to tan, some with cleft tips, most approximately one interval long and most shorter than first metatarsomere; surface texture very slightly shagreened; at second and third puncture rows at middle, punctures separated by a distance approximately equal to 3 times their length, separation of rows approximately equal to width of 5-6 punctures; basal maculation consisting of dense relatively sparse patches of white, recumbent, coarse setae; maculation at apical quarter consisting of a thick transverse band with white, recumbent, coarse setae; margin slightly shallowly notched inwards at apex. Male genitalia. Elongate, parameres narrow, median lobe moderately narrow and short ( Figure 6C).

Etymology
The species name is the Latin noun "periculum" [danger], referring to Danger Point, a place with offshore rocks treacherous to shipping and close to the known distribution of this species. The specific epithet is a noun in apposition.

Figures 4, 6D, 7 Diagnosis
This species can be distinguished from its sympatric congeners with the following combination of characteristics: a narrow median pronotal cleft that is no more than 3 elytral punctures wide; pronotum in anterior view notably rounded, with little dorsal cleft visible; interpuncture setae brown, short, the same length as the width of one interval; and interrupted transverse maculation on apical quarter of each elytron. Size range: 1.9-2.3 mm

Description
Head. Dark red-brown; setae predominately orange-brown and occasionally silvery, some with cleft tips; relatively smooth glabrous patch centrally located on vertex, rest of surface rugose and densely covered with moderately sized punctures; interantennal ridge as wide as diameter of about 1.5 ommatidia, with a few brown, recumbent setae; eyes subcircular, at maximum diameter approximately two-thirds the length of scape; antennomeres 3-10 equal in size, penultimate antennomere at widest point approximately equal to half its length, ultimate antennomere 1.5 times as long as penultimate, covered with silvery setae. Pronotum. Dark red-brown; setae brown, fine, long; large median lobes slightly expanding dorsad; median cleft long, shallow, in dorsal view approximately two thirds total length of pronotum measured from anterior margin to transverse cleft at base, inner sides narrowly separated, approximately 2 elytral punctures wide at narrowest point, parallel at middle to posterior end, very slightly diverging anteriad, expanding out laterally obliquely to small lateral cleft; lateral spines present; three dorsally projecting basal cleft spines sparsely covered with a sparse layer of brownish-yellow setae, setae largely absent from space between spines. Elytra. Dark red-brown approaching black; interpuncture setae orange-brown or tan, lacking cleft tips, most approximately one interval in length, some approaching 2 intervals in length, and typically shorter than first metatarsomere; surface texture smooth; at second and third puncture rows at middle, punctures separated by a distance approximately equal to 3-4 times their length, separation of rows approximately equal to width of 5 punctures; basal maculation consisting of dense, elongate patches of coarse, white recumbent setae; maculation at apical quarter consisting of a thin, obliquely transverse patch of coarse white, recumbent setae, some with cleft tips; narrow transverse band of coarse, white, recumbent setae near apex; margin obscurely notched at apex. Male genitalia. Moderate in length, parameres moderate in width, median lobe moderately broad and short ( Figure 6D).

Etymology
The name is derived from the Greek words "stenos" [narrow] and "chasma" [abyss, chasm], referring to the narrow median pronotal cleft of this species. The specific epithet is a noun in apposition.

Figures 5, 6E, 7 Diagnosis
This species is only known to occur on the northern face of the Swartberg mountains in the Western Cape. It can be distinguished by the following combination of characteristics: dark brown to black cuticle; median lobes dorsally pronounced; interpuncture elytral setae length about the width of two to three intervals, orange-brown and the maculation at apical quarter of the elytra composed of a sparse, transversely oblique band of white setae. Size range: 2.2-2.7 mm Description Head. Dark brown; setae predominately orange-brown and silvery, recumbent, long, some with cleft tips; small glabrous patch on vertex not visible on type specimens due to head position, rest of surface densely rugose; interantennal ridge as wide as diameter of 2-3 ommatidia, with few orange-brown setae present; eyes subcircular, at maximum diameter approximately equal to one half the length of scape; antennomeres 3-10 equal in size, penultimate antennomere at widest point approximately equal to half its length, ultimate antennomere 1.5 times as long as penultimate, covered with silvery setae. Pronotum. Black; setae orange-brown, fine, long; median lobes large, pronounced, expanding dorsad, median cleft in dorsal view approximately half length of pronotum measured from anterior margin to transverse cleft at base, inner sides approximately parallel for half length, as wide as 4-5 punctures at the narrowest point, slightly diverging posteriad, slightly diverging anteriad near anterior end, expanding laterally obliquely to small lateral African Entomology 2023, 31: e13198 (7 pages) https://doi.org/10.17159/2254-8854/2023/a13198 cleft; lateral spines present; three dorsally projecting basal cleft spines covered with a thick layer of yellow-brown setae, setae absent from spaces between spines. Elytra. Black; interpuncture setae orange-brown, long, most approximately 2-3 intervals in length and longer than first metatarsomere; surface texture smooth; at second and third puncture rows at middle, punctures separated by a distance approximately twice their length, separation of rows approximately equal to width of 5-6 punctures; basal maculation consisting of dense patches of short, coarse, white, recumbent setae; maculation at apical quarter consisting of a transversely oblique band of sparse, coarse, white, recumbent setae; margin slightly notched at apex. Male genitalia. Elongate, parameres narrow, median lobe narrow and short ( Figure 6E).

Etymology
This species is named after the Swartberg mountain range, where it is known to occur. The specific epithet is an adjective.

NOMENCLATURAL CORRECTIONS
Six of the nine specific epithets of Pseudomezium species proposed by Smiley & Philips (2011) are not in accordance with the appropriate latinisation recommended by the International Code of Zoological Nomenclature (the Code, ICZN 1999). Apart from gender agreement, the inappropriately formed linguistic structures cannot be corrected. Since these errors are not inadvertent, they are not incorrect original spellings in the sense of Articles 32.4 and 32.5 of the Code, and they stand as they are. On the other hand, adjectival species names that do not agree in gender with the genus name (Article 31.2) requires mandatory correction (Article 34.2).
Among the six problematic Pseudomezium species names, half are both inappropriately formed and gender-noncongruent. The inappropriate latinisations may not be corrected, but below we correct the gender endings of those names. Smiley & Philips (2011) did not indicate whether their new species names are to be regarded as nouns or adjectives. To establish which Pseudomezium names are gender-noncongruent, a necessary step was to distinguish between adjectival or participial species names and those that act as nouns, a decision which was in a number of cases not clear cut. The etymologies provided by the species authors were hence employed as contingent evidence.
Article 31.2.3 (ICZN 1999) rules that if a species name's final component word (throughout applicable here) is not a Latin or latinised word, it is to be treated as indeclinable, hence remaining unchanged. This would be a preferred option vis-à-vis nomenclatural stability, but could not be applied to all of these specific epithets since the authors throughout either stated that their stem words are Latin, or implied that the components of their compound names are latinised "from the Greek" [sic]. Even if Smiley & Philips's (2011) species names were irregularly formed, they still allow the application of the Code's Article 26, which mandates the assumption of Greek or Latin in scientific names.
The grammatical gender of the genus name Pseudomezium is neuter. In our view, the specific epithets in the following four combinations act as adjectives, but were not originally proposed with corresponding neuter gender. In accordance with Article 34.2 (ICZN 1999), these four names are here corrected as follows: • Pseudomezium brunneaurant. Original etymology: "from the Latin words 'brunne' meaning brown, and 'auranti' meaning orange." Note that the latter component is interpreted as a colour, not as a fruit. Corrected name: Pseudomezium brunneaurantiacum.  Smiley & Philips's (2011) species names P. aspricorpus and P. noacanthus should not be changed, since we consider the specific epithets in these combinations to be nouns in apposition to the genus name (Articles 31. 2.1 and 34.2.1, ICZN 1999). Selection of this option was encouraged by our wish to maximise nomenclatural stability. The remaining three species names coined by Smiley & Philips (2011), P. brucei, P. darae and P. effieae, all three patronyms, pose no grammatical or Code-compliance problems.

KEY TO THE DESCRIBED SPECIES OF PSEUDOMEZIUM
When identifying species of Pseudomezium, one should be aware of broken or abraded setae that may hamper identification. The lengths of the erect elytral setae between the puncture rows are generally somewhat variable, but most will be within the range given in the key and descriptions. Male genitalia and the collecting locality will assist identifications.