Hydnum subconnatum Swenie & Matheny

Swenie, Rachel A., Baroni, Timothy J. & Matheny, P. Brandon, 2018, Six new species and reports of Hydnum (Cantharellales) from eastern North America, MycoKeys 42, pp. 35-72 : 35

Hydnum subconnatum Swenie & Matheny sp. nov. Figs 4A, 5L

Diagnosis.

Closely related to Hydnum oregonense but differs from it by ITS sequence divergence and geographic distribution. Hydnum subconnatum is known only from the southeastern U.S.

Type.

UNITED STATES. North Carolina: Yancey County, Carolina Hemlocks Recreation Area, picnic area (35.8057; -82.2047), on soil growing in fused cluster and singly with Tsuga carolinensis , Quercus , Liriodendron , 840 m, 29 Sep 2017, R.A. Swenie RAS235 (holotype: TENN 073064).

Etymology.

subconnatum (L.), born together, in reference to the fused stipe bases of multiple basidiomes.

Description.

Pileus 10-75 mm wide, more or less round, broadly convex to plane, surface usually dry but sometimes slightly hygrophanous, glabrous, occasionally with shallow cracks or pits in age, sometimes umbilicate or with central depression, peach orange (6C8-6B7) to reddish-brown ( “Cinnamon-Rufous”); margin incurved and entire, becoming eroded or split and sometimes wavy in age. Spines 1-8 mm long, shortest near margin, adnate to subdecurrent, white to pale orange (5A4, 6A3). Stipe 15-60 × 5-20(30) mm, central or eccentric, equal or widening to bulbous base, sometimes with up to four basidiomes fused together at base, texture smooth, white to dull tan, bruising orange-brown (6B8-7D7 or “Ochraceous-Buff”). Context fleshy, white to dull cream-brown, staining not observed. Odor mild or slightly sweet. Taste mild.

Basidiospores 8.5 –8.9– 10 μm × 7.5 –8.5– 9.5(10) μm, Q= 1.00 –1.05– 1.14(1.20) (n=34/3), globose to subglobose, smooth, hyaline in KOH. Basidia 48-61 × 8.5-10.5 μm with 3-4 sterigmata. Pileipellis an interwoven cutis, hyphae smooth, cylindrical, thin-walled, mostly 4-6 μm wide. Clamp connections present.

Distribution.

Southeastern U.S. - North Carolina (type), Tennessee, and Georgia.

Ecology.

In mixed woods with Quercus , Pinus , Tsuga , Fagus , Betula , Carya , Liriodendron . July to December.

Other specimens examined.

UNITED STATES. Georgia: Chatham County, Wormsloe Plantation, in duff with Quercus , Pinus , 8 m, 26 Dec 1976, J.H. Restivo JHR40605 (TENN 040605). White County, Unicoi State Park, Unicoi to Helen Trail, solitary beside trail with Pinus and mixed hardwoods, 460 m, 16 Jul 2017, J.E. Uehling RAS165 (TENN 073026). White County, Unicoi State Park, Unicoi to Helen Trail, solitary beside trail with Pinus and mixed hardwoods, 460 m, 16 Jul 2017, R.A. Swenie RAS169 (TENN 073048). Tennessee: Great Smoky Mountains National Park, under Pinus , Tsuga , Quercus , Acer , Meig’s Creek Trail, 580 m, 30 Sep 2004, E.B. Lickey TFB12311 (TENN 060359). Great Smoky Mountains National Park, Cades Cove, scattered in mixed forest with Fagus , Quercus , Carya , Pinus , 520 m, 23 Nov 2013, R.A. Walter RAW18 (TENN 073005). Great Smoky Mountains National Park, Schoolhouse Gap Trail, scattered beneath Pinus , Tsuga , Quercus , Betula , 550 m, 26 Oct 2013, K.E. Rewcastle KER016 (TENN 073006). Great Smoky Mountains National Park, trail to Look Rock fire tower, some caespitose and forming a ring among Quercus litter on trail, 800 m, 17 Nov 2009, E.E. Austin EEA171109-1 (073744). Great Smoky Mountains National Park, Trillium Gap Trail, 9 Jul 2017, B.P. Looney BPL931 (TENN 073028). Big Ridge State Park, Ghost House Loop Trail, scattered to caespitose under Quercus , Fagus , Carya , Pinus virginiana , 320 m, 9 Nov 2015, R.A. Swenie RAS053 (TENN 070846).

Discussion.

Hydnum subconnatum is known from the southeastern U.S. in a range of low elevation mixed forests such as oak-pine or hemlock-pine mixed with oak and beech. All known specimens are reported under 1000 m elevation. Basidiomes can occur in caespitose clusters with the stipe bases and two or more pilei fused together. The pileus coloration is highly variable, however, ranging from deep orange to pale peach and fading to tan towards the margin, making this a difficult species to distinguish at a glance. Hydnum caespitosum Banning ex Peck (non H. caespitosum Valenti), described from Maryland, occurs "at roots of trees and near old stumps" and is much paler in coloration, depicted by Banning in her painting as a yellowish species. Furthermore, our examination of the holotype of H. caespitosum revealed that basidiospores are much smaller in that species than in Hydnum subconnatum . The new name H. geminum is proposed below for H. caespitosum Banning ex Peck.

Specimens of H. subconnatum form a monophyletic group with support values <70% (ML) and <0.95 (BI). ITS sequence variation is relatively low (<1%) among sampled specimens of H. subconnatum , but the clade is highly dissimilar (8% sequence divergence) from Mexican taxa (Genbank KR135344-KR135345) that form a well-supported sister lineage.