Paussus (Hylotorus) abditus Nagel, 2018

Abdel-Dayem, Mahmoud S., Rasool, Iftekhar, Elgharbawy, Ali A., Nagel, Peter & Aldhafer, Hathal M., 2018, Faunistic inventory and zoogeographical analysis of the ground beetles (Coleoptera, Carabidae) of Garf Raydah Nature Reserve, Southwestern of Saudi Arabia, and description of a new species of Paussinae, Zootaxa 4514 (3), pp. 341-371 : 355-358

Paussus (Hylotorus) abditus Nagel , sp. n.

( Figure 2 )

Holotype (hereby designated): Male; dry-mounted, glued on rectangular, pinned card; antennal clubs, left foreleg, left hind leg detached, labium dissected and glued on same card.

Original labels (rectangular) (verbatim): 1. Yellow label, handwritten by A. Raffray: “ Sufamila [or Jutamila or Sutonnila or similar, partly illegible] / Raff. ” (nomen nudum, unavailable). 2. White label, printed: “El Hajaz / Millinger [sic!]”. 3. White label, printed: “A. Raffray”. 4. White label, printed: “E. Wasmann / vidit 1904”.

Added labels: 1. Red, rectangular, printed: “ Holotypus / Paussus abditus / P. Nagel, 2018”. 2. White label, printed: “ ♂ ”.

Holotype repository: Muséum National d’Histoire Naturelle , Paris, France ( MNHN).

Paratype: Female; dry-mounted, glued on pointed, pinned card; right antennal club absent, tip of abdomen opened and rearranged, gonostyli dissected and glued on card with specimen.

Original labels (white, rectangular) (verbatim): 1. printed, “ KSA, Asir, Abha, Raydah / 18°12.095' N 42°24.536' E, 2578 m. / 08. VI.2014, PT- 3 / Al Dhafer, H.; Fadl, H.; Abdel-Dayem, / M.S., El Torkey, A.; El Gharbawy, A.”. 2. printed, “ ♀ ”. 3. handwritten, “sp.1543 / Paussus sp.”.

Added label: White, red frame, rectangular, printed: “ Paratypus / Paussus abditus / P. Nagel, 2018”.

Paratype repository: King Saud University Museum of Arthropods ( KSMA), King Saud University, Riyadh, Kingdom of Saudi Arabia .

Type locality: Arabian Peninsula, Western Kingdom of Saudi Arabia, Hejaz Mountains.

Note: The type specimens were collected by Charles Millingen, M.D., Edinburgh at around the 1870ies (labels with collector “Millingen” exist with localities El Hejaz / Hajaz, Jeddah and Yemen, and the name is sometimes printed “Millinger”).

Etymology: The specific epithet is the Latin adjective for “hidden” or “undiscovered”. It refers to the fact that this species remained undiscovered for more than 100 years until a second specimen was discovered.

Diagnosis. A small Paussus of the P. cucullatus group sensu lato; characterized by a tumid antennal club with small, projecting anterior basal angle and large, apically broadly rounded posterior basal angle; antennal club with excavation not extending up to apex; head with vertex produced, forming two apically rounded protuberances; two cephalic openings vestigial, hardly discernible; anterior pronotum with blunt and low transverse collar; pronotal trichome well developed; pygidium with lower (posterior) margin with dense fringe of hair; hind tibiae compressed and strongly widened.

Description of male holotype specimen ( Figure 2 ). Standardized body length from tip of head to tip of elytra 4.1 mm, width across mid-elytra 1.5 mm. Body with dorsal and lower side, legs and antennae brown, frontal margins of head and frontal margins of posterior part of pronotum narrowly black. Head, pronotum, elytra with dorsal pubescence of scattered, short, light, lanceolate, narrowly scaliform, apically rounded setae; middle of posterior pronotum glabrous, smooth, glossy; pubescence of appendages equally scattered yet of thinner setae; setae mostly erect to slanting, more appressed at lateral head and antennomere I. Surface shiny except frontal head, neck and antennomere I (scape) with fine, matte microsculpture; punctuation inconspicuous, only scape with coarse, dense punctures; elytra weakly rugose.

Head almost as long as wide, with frontal margin notched in the middle and frontal lobes broadly rounded; eyes slightly vaulted; temples not projecting, at dorsal view forming a regular curve with eye; vertex produced in two rounded protuberances, separated by shallow longitudinal emargination; cephalic openings on top of protuberances vestigial, closed, indicated by small, shallow, oval impressions, difficult to see. Antennomere I devoid of well-marked longitudinal edges; antennal club boat shaped, 1.5 times longer than wide (basal tooth disregarded), tumid; frontal margin of the club with two fenestriform pits near base; anterior basal angle of club small, acute; posterior basal projection large, apically rounded; hind part of the club with large posterior excavation comprising the basal two thirds only; at posterior view dorsal and ventral margins of excavation undulate of four and five tumid tubercles, each with 1 to 3 apical setae; club with distinct tuft of setae (trichome) near ventral base. Labrum with anterior margin weakly emarginate. Maxillary palpomeres similar to Figs 6G,H in Robertson and Moore (2016); palpomere II large, approximately as long as wide, with mesal margin almost straight, mesal apical angle broadly rounded, outer margin rounded with apical angle not produced; maxillary palpomere II three times wider than following palpomere; palpomere III and IV subequal in length, III little wider than terminal palpomere. Lacinia bifalcate (as usual), moderately setose, with 7–8 setae at anterior margin. Labial palpomeres similar to Figs 6C, 7N in Robertson & Moore (2016); palpomere III long, narrow, 4.5 times as long as wide, apically rounded. Ligula at ventral view with longitudinal carinula on disc; apical margin bisinuate with apical median margin broadly rounded and lateral anterior angles produced anteriorly. Gula: width/length ratio of gula at narrowest point 0.6.

Pronotum hardly wider than long, transversely bipartite, with large trichomes at both ends of groove; anterior part little wider than head, low, with transverse dorsal edge of collar-like structure broadly rounded, slightly emarginated in the middle, lateral angles little produced; posterior part narrowed towards base. Elytra with even, scattered pubescence; hindwings present.

Fused abdominal ventrites 1–3 with scraper of stridulatory organ present (synapomorphic character of Paussus L. s.l.). Pygidium with disc flat and lower (anatomically posterior) margin narrowly explanate, dorsally (apically) set with dense fringe of long hair, ventrally with series of short, separate setae. Legs (femora and tibiae) from the front to the back increasingly more compressed and dilated, hind tibiae twice as long as wide; tibial terminal spurs absent; terminal tarsomere of posterior tarsus as long as three preceding ones together; tarsomeres ventrally without setulose pads.

Additional description of female paratype: The description of the male holotype specimen fits also to the female paratype, with a few additions as follows. The pubescence is partially rubbed off; the cephalic pores are virtually absent and at close inspection only recognizable as a minute, longitudinal, slightly darkened structure, possibly a remnant of part of the pores’ margin; eyes little smaller than in male and hardly vaulted; hind tibiae even shorter and wider than in the male; the gonocoxae were dissected, the diverging tips are of normal shape of Paussus s.l.;

Host ant: Unknown

Ecology: The female paratype specimen was sampled in the African pencil cedar woodland at 2578 m in the GRNR ( Figure 3 ). Description of habitat see chapter “study area” above. The specimen was recovered from a pitfall trap.

Distribution. Saudi Arabia: Hejaz Mountains (exact locality unknown); Asir, Abha, Raydah, 18°12.095' N 42°24.536' E.

Life forms. Myrmecophilous (M) species.

Remarks. The new species is assigned to Paussus subgenus Hylotorus Dalman, 1823 , according to the phylogenetically based classification of Robertson and Moore (2016) (cf. Nagel et al. 2017a). The description of P. abditus sp. n. given here above matches generally well the diagnosis and characters used in their key. Deviations are the very long and narrow labial palpomere III and the slightly higher number of setae at the anterior margin of the lacinia in the present new species.

Paussus (Hylotorus) abditus sp. n. is a member of the P. cucullatus group sensu lato, an African lineage of Paussus subgen. Hylotorus . The new species is distinguished from the Afrotropical P. cucullatus group s. str. (all species considered in the key of Nagel (2006), including the recently described P. huamboensis Schüle & Bednařík, 2015 ) by its tumid antennal club with much smaller excavation, the low anterior part of pronotum and the vestigial cephalic openings. Paussus excavatus has an elongated, flattened antennal club and well-developed cephalic openings. Paussus conradti Kolbe, 1896 , also has the cephalic openings present, with the anterior basal angle of the antennal club obliterated and the lower (posterior) pygidial margin set with a series of separated long tufts of hair ( Nagel 2006; Fig. 2 ).

Paussus abditus sp. n. is similar to P. cyathiger Raffray, 1886 ( Ethiopia) , the holotype and one paratype of which was made available to us due to the courtesy of Ms. Taghavian-Azari (MNHN). This new species differs from P. cyathiger mainly by the posterior basal angle produced into a broad process rather than a thin, long peg as in P. cyathiger .

NB: the specimen illustrated and cited as P. cyathiger by Luna de Carvalho (1974, 1989) is a still undescribed species. The head of the actual P. cyathiger is devoid of an anterolateral trichome (setose pad), the upper and hind margins of the antennal club are both devoid of tubercles or teeth, and the posterior basal angle of the club is produced into a long, thin, apically blunt peg.

Paussus abditus sp. n. seems to be most similar to Paussus rougemontianus Lorenz, 1998 ( Yemen) (replacement name for Cochliopaussus rougemonti Luna de Carvalho, 1989 ). The antennal club of P. rougemontianus has the posterior excavation shallow and restricted to the basal half of the club.

The other Arabian member of Paussus subgenus Hylotorus is P. cephalotes Raffray, 1886 . This bizarre species is unmistakable by the shape of the antennal club and the two horn-like projections of the head. All Arabian Paussinae are members of the species-rich genus Paussus L. Till date 8 species were reported from the Arabian Peninsula sensu lato, as follows ( Nagel 1982; Luna de Carvalho 2000b; Nagel et al. 2017b): P. arabicus Raffray, 1886 ; P. brittoni Reichensperger, 1957 ; P. cephalotes Raffray, 1886 ; P. cirenaicus Fiori, 1914 ; P. piochardi Saulcy, 1874 ; P. rougemontianus Lorenz, 1998 ; P. thomsonii Reiche, 1860 ; P. turcicus (Frivaldszky 1835) (the latter has its southernmost localities in Israel and Jordan). The specific identity of P. piochardi and P. cirenaicus within the more inclusive P. crenaticornis Raffray, 1886 group is debated. P. abditus sp. n. increases the number to nine species.

According to the current state of knowledge four species are exclusively known from the Arabian Peninsula sensu lato and are possibly endemics (END_AR): P. abditus sp. n. (only known from SA), P. brittoni , P. cephalotes , P. rougemontianus . Their range comprises Yemen and the Hejaz and Asir mountains in KSA which run parallel to the Red Sea coast.

Figures

FIGURE 2. Paussus (Hylotorus) abditus sp. n. holotype specimen from the Hejaz mountains. The illustration shows the specimen with the appendages of the right side at their broadest view, while the left antennae and legs are shown twisted through 90 degrees, i.e. at their narrowest view (cf. Nagel 2006). The inset shows the “collar” of the anterior pronotum at frontal view. Scale bar: 1 mm. Illustration: E. Weber, Basel, Switzerland. Copyright: P. Nagel.

FIGURE 3. Photographs of the type locality for paratype of Paussus (Hylotorus) abditus sp. n. in the African pencil cedar woodland at 2578 m, at Garf Raydah Nature Reserve, Asir Province, southwest of the Kingdom of Saudi Arabia.