Caelostomus rotundiformis Kavanaugh and Rainio, 2016

Kavanaugh, David H. & Rainio, Johanna, 2016, Twenty-six New Species of Predaceous Ground Beetles (Coleoptera: Adephaga: Carabidae) from Ranomafana National Park, Madagascar, Proceedings of the California Academy of Sciences 63 (7), pp. 201-268 : 209-211

Caelostomus rotundiformis Kavanaugh and Rainio , sp. nov.

Figure 5

Caelostomus n. sp. 1; Rainio 2009: 31, Rainio 2012: 62 (informal designation).

TYPE MATERIAL.— Holotype ( Figs. 5A–B ), a female, in CAS, labeled: “ MADAGASCAR Ranomafana NP., Vatoharanana , Trail K at 50 m mark, 07.06.2000 ”/ “collected by hand in daytime, F. Ratalata & J. Rainio collectors”/ “13.” [handwritten label]/ “7.6.00 K 50” [handwritten label]/ “ HOLOTYPE Caelostomus rotundiformis Kavanaugh & Rainio sp. n. 2015” [red label]. Paratypes (only 1): a female (in MNHN) labeled “ MADAGASCAR Ranomafana NP. Talatakely, C1450 11.3.2004 Johanna Rainio leg.”/ “112.” [handwritten label]/ “ PARATYPE Caelostomus rotundiformis Kavanaugh & Rainio sp. n. 2015” [yellow label].

TYPE LOCALITY.— Madagascar, Fianarantsoa Province, Ranomafana National Park .

DERIVATION OF SPECIES NAME.— The species epithet, rotundiformis , is an adjective derived from the Latin words, rotundus, meaning round, and forma, meaning form or shape. The name refers to the very short, broad, rounded form of members of this species.

RECOGNITION.— Size moderately small for genus, SBL = 5.4–5. 5 mm (females only), body form ( Fig. 5A ) short and broad, ratio SBL/EW = 1.97–2.01. This species is undoubtedly a member of genus Caelostomus as conceived by Jeannel (1948), although we cannot confirm this based on his key because he used male features only in two couplets to distinguish Caelostomus members from those of several other genera and we have only female specimens. However, we examined specimens of all species in all the other Malagasy caelostomine genera while at MNHN and confirmed that this species represents none of them. Observable female features, including body form short and broad, frontal furrows simple, not doubled, parascutellar striae of elytra indistinct, basal setiferous pore situated at base of elytral stria 3, tarsomeres not densely setose ventrally, and anterior tarsomere 4 not bilobed apically ( Fig. 5C ), are consistent with Caelostomus females. Within this genus, members of C. rotundiformis share the following features with those of other species of the nominate subgenus: head with frons and frontal furrows smooth, impunctate; elytral base distinctly margined from humerus medially to base of stria 3 or 2; elytral striae 6 and 7 deeply impressed throughout, not effaced apically; lateral elytral intervals narrow, moderately convex; apical part of umbilicate series of setiferous pores not inserted in a deep groove; and female apical abdominal ventrite with (two or) three pairs of setae subapically. However, members of this species confound Jeannel’s (1948) key to species of Caelostomus s. str. Their short and broad elytra (ratio EL/EW = 1.13–1.15) are shared with members of the convexiusculus species group, but their elytral striae are impuncate, whereas those of other species group members are markedly punctate throughout their length. Within the group, their small size (less than 6.0 mm) is shared with Caelostomus humilis ( Tschitschérine 1903) , Caelostomus minisculus Straneo (1940) , and Caelostomus minutissimus Jeannel (1948) ; however, members of these three species are even smaller (SBL = 5.0 mm or less) and, again, have markedly punctate elytral striae. The striae in C. rotundiformis members are smooth, without evident punctures, and the shape of the pronotum ( Fig. 5A ) is markedly different, with lateral margins evenly arcuate throughout their length and hind angles markedly obtuse. This species probably represents a distinct species group of its own within subgenus Caelostomus in Madagascar.

GEOGRAPHICAL DISTRIBUTION.— At present, known only from the type locality.

HABITAT DISTRIBUTION.— The holotype of this species was collected by hand in daytime in primary montane rain forest in the Vatoharanana area at an elevation of 1200 m, along Trail K at the 50 meter mark. The paratype specimen was collected in a pitfall trap in secondary montane rain forest in the Talatakely area at an elevation of 900 m, along Trail C at the 1450 meter mark.

Figures

FIGURE 5. Digital images of holotype female of Caelostomus rotundiformis Kavanaugh & Rainio sp. nov. A. Habitus, dorsal aspect; B. Labels; C. Right anterior tarsus, dorsal aspect. Scale line A = 1.0 mm, C = 0.5 mm.