Tomarus subtropicus
Creators: name: López-García, Margarita M.
name: Deloya, Cuauhtémoc
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Dynastidae
Tomarus
Tomarus subtropicus

description: Tomarus subtropicus (Blatchley, 1922)
(Figs. 2K, 4I, 6G, 13K, 14H, 16R, 20I, 28I; 41)
Ligyrus subtropicus Blatchley, 1922: 30. Original combination.
Female holotype (PERC) “Dunedin, Fla. / W.S.B. Coll. / 6-4 /.1913 // Purdue / Blatchley / collection // TYPE // Ligyrus / subtropicus / sp. nov. // PERC / 0066475”. Type locality: Dunedin, Florida.
Ligyrus blatchleyi Cartwright, 1944: 34. Synonym.
Male holotype (USNM) not examined. Allotype (USNM) “Miami, Florida / 20.Jun.1933 / Frank N. Young // ALLOTYPE / USNM / 56936 // Ligyrus / blatchleyi / Cartwright / Allotype // Bothynus subtropicus (Blatchley) / Det. Cartwright 1958 // Tomarus subtropicus / (Blatchley) / Det. B.C. Ratcliffe 2015 ”. Two female paratypes (USNM) “Miami / 25.Jun.1933 / Frank N. Young // PARATYPE / USNM / 56936 // Ligyrus / blatchleyi / Cartwright / Paratype // Bothynus subtropicus (Blatchley) / Det. Cartwright 1958”. Two female paratypes (USNM) “Miami / 22.Jun.1933 / Frank N. Young // PARATYPE / USNM / 56936 // Ligyrus / blatchleyi / Cartwright / Paratype // Bothynus subtropicus (Blatchley) / Det. Cartwright 1958”. Female paratype (USNM) “Miami / 16.May.1933 / Frank N. Young // PARATYPE / USNM / 56936 // Ligyrus / blatchleyi / Cartwright / Paratype // Bothynus subtropicus (Blatchley) / Det. Cartwright 1958”. Male paratype (USNM) “Miami / 30.Jun.1933 / Frank N. Young // PARATYPE / USNM / 56936 // Ligyrus / blatchleyi / Cartwright / Paratype // Bothynus subtropicus (Blatchley) / Det. Cartwright 1958”. Male paratype (USNM) “Savannah Ga. / 13.Jul.1937 / P.W. Fatting // PARATYPE / USNM / 56936 // Ligyrus / blatchleyi / Cartwright / Paratype // Bothynus subtropicus (Blatchley) / Det. Cartwright 1958”. Another five paratypes not examined. Type locality: Miami, Florida, United States of America.
Description. Habitus as in Fig. 28I. Length 17.5–27.5 mm; humeral width 8.8–14.0 mm. Color dark reddish brown to black. Head: Frons and clypeus coarsely and densely rugose. Frontoclypeal region with 2 transverse, low tubercles separated by about 7 tubercle diameters. Clypeus narrowed towards apex, base 3 times wider than apex. Clypeal teeth small, transverse, separated by a tooth diameter. Mandible with 2 apical teeth and a lateral, narrowly rounded tooth. Mentum abruptly constricted at apical 3rd (Fig. 2K). Galea of maxilla with teeth 5 and 6 vestigial (Fig. 4I). Interocular distance 3.5 times an eye width. Pronotum: Surface with small punctures, denser and deeper on anterior and lateral angles, disc impunctate. Apical tubercle small, rounded, visible in lateral view. Subapical fovea shallow, elongate, narrow (1/3 the interocular distance); equal in both sexes, surface rugopunctate. Scutellum: Surface with sparse, minute punctures not forming lines parallel to margins. Elytra: Punctures on first interval as large as those on other intervals, sutural stria complete. Inner surface of apex with rounded, large tubercles forming 17 parallel lines. Abdomen: Apex of tergite IV with a triangular wide area with small, irregular tubercles forming 12–14 diagonal, nearly parallel lines. Pygidium with dense rugosity on basal 3rd, apex rounded. Venter: Apex of prosternal process flat, transversely oval to rounded. Metasternum with minute setae. Legs: Protibia tridentate, rarely with basal denticle. Apex of metatibia crenulate, with 11–14 spinules. Female genitalia: Coxite concave near the inner margin (Fig. 13K). Male genitalia: Spiculum gastrale without basal plates (Fig. 14H). Phallobase 1.2 times longer than parameres. Parameres with 2 dorsal teeth each side; basal tooth large, strongly curved backwards, longer than apical tooth that is short (Figs. 16R, 20I). Internal sac with copulatory lamella and short lamellar spiny belt; with a complex of 7 spine-like, accessory lamellae, with dense granules at base.
Diagnosis. Tomarus subtropicus can be differentiated by the following character combination: frontoclypeal tubercles transverse and low (as in T. adoceteus, Fig. 1H); galea of maxilla with teeth 5 and 6 vestigial (Fig. 4I); pronotal surface with small punctures (Fig. 28I); pronotal tubercle small but visible in lateral view; pronotal fovea shallow and narrow (1/3 as wide as interocular distance); protibial tridentate, rarely with an additional basal denticle; apex of metatibia with 11–14 spinules; parameres with 2 dorsal teeth on each side, main teeth long and strongly curved backwards, secondary teeth short (Figs. 16R, 20I).
Distribution. Southeastern United States of America (Endrödi 1985; Ratcliffe & Cave 2017).
Locality records (Fig. 41). 125 examined specimens from FSCA, UNSM, USNM. Counties listed from Ratcliffe & Cave (2017). UNITED STATES OF AMERICA (492). Alabama (1): Mobile. Florida (459): Alachua; Baker; Broward; Calhoun; Charlotte; Collier; Dade; Dixie; Duval; Franklin; Hendry; Hillsborough; Indian River; Lee; Manatee; Monroe; Palm Beach; Pinellas; Sarasota; Seminole; St. Lucie; Taylor; Volusia. Georgia (6): Chatham; Glynn. Lousiana (18): Lafourche. South Carolina (8): Beaufort; Charleston.
Natural history. The species is univoltine. Adults emerge between June and August, eggs are laid from late June to early August, and larvae are active from July to February (Kostromytska & Buss 2008); winter is passed as a larva. The larva was described by Gordon & Anderson (1981). It is considered the species of Scarabaeidae of primary economic importance in sugar cane fields in the United States of America (Cartwright 1959; Gordon & Anderson 1981) but also attacks the roots of other grasses (Stenotaphrum secundatum (Walt. Kuntze) and Cynodon dactylon (L.) (Poaceae) (Kostromytska & Buss 2011). The females of T. subtropicus lay their eggs at the base of the plant, and then the larvae feed on the roots until the plant lacks support. Cherry et al. (2017) sampled 20 fields of sugar cane in Florida during 2015 and 2016 and found that although T. subtropicus was once the most abundant white grub in this region, no specimens were found. They believed that the most logical explanation for this drastic population decline is the increased flooding of sugarcane fields as this species is less flood tolerant compared with wireworms.
description: Published as part of López-García, Margarita M. & Deloya, Cuauhtémoc, 2022, Cladistic analysis reveals polyphyly of Tomarus (Coleoptera: Scarabaeidae: Dynastinae): new classification and taxonomic revision, pp. 1-119 in Zootaxa 5211 (1) on pages 71-72, DOI: 10.11646/zootaxa.5211.1.1, http://zenodo.org/record/7345007